If those were the sort of readings you got, then I would be concerned about parasites on your female guppy. "Over the phone" it is hard to determine what might be ailing her. The best bet would be gill flukes, which are common among livebearers from shops. I was surprised to read that they often are there in "non-lethal levels." When a fish is purchased and moved or stressed in some other way, their resistance to flukes and other maladies goes down and the parasites multiply. Fortunately treatments for gill flukes also deal with a lot of other parasites too. :)

If your tests do reveal that your tank has the very toxic ammonia or some what less toxic nitrites or too many everyday toxic nitrates in the water, keep up the partial water changes - even daily if possible. If you did a 25% water changes yesterday, do a 30% today or tomorrow. Then walk up those water changes to 35%, 40% and 45%.

If you don't have any "food quality," soap-less holding containers to season water in, please consider getting some. For people with a 10-gallon aquarium one of the quickest "fixes" is to buy 3 or 4 gallons of "drinking water" from your local grocery. Buy the best price. Don't get nursery water or water intended for mixing an infant formula. That nursery water may be straight RO (Reverse Osmosis). Like Distilled or DI water, the RO water has virtually no minerals in the water. It can kill your fish if added in large quantities!

The drinking water is often RO water, but it has been "rebuild" with quantities of calcium, magnesium and potassium (which vary some by brand). You can gradually add that as your next water change. If you can leave the jugs open for a time and make sure the temperature is the same as that in the tank, so much the better.

Then put the appropriate amount of whatever water conditioner has been recommended for your tap water (and there are differences!) Leave the tops of those holding containers open to dissipate carbon dioxide, freed up chlorine and free nitrogen in your tap water and allow the water to absorb at least a tiny bit of free oxygen. If your tank hood is strong enough AND the lights are not on, I might even leave the jugs on the tank top (overnight or while at work), once the water has warmed up some, so that temperatures are about the same. I use pretty strong pieces of glass as tank tops and can get away with that.

If water conditions are really dire, you can drop some money for a material which can be put into your filter (cut to size if necessary). Polyfilter and a bunch of other products, which your LFS or live fish shop will cheerfully sell you. I would only leave that material (or bag of material) there long enough to drop the ammonia to zero and then I would take it out. If the ammonia absorbers are there for a long time, the beneficial bacteria will starve and your nitrogen cycle will be nil.

If your water conditions are fine in terms of waste material, consider treating with Praziquantel or some combination of meds with it in. Many times the younger employees of a store will not know the contents of their treatments. Jungle and other companies are getting much better about listing their medications in their treatments for external parasites.

It probably would be best if you could treat the tank with Praziquantel (an anthelmintic) or a combination of anthelmintics rather than a complete combination which includes antibiotics or the quite effective, but potentially dangerous organophosphates.

For instance PetSmart sells the product called Gel-Tec Ultra Cure PX. It contains Parziquantel in combination with Levamisole and the antibiotic Metronidazole. I use that as a preventative treatment in quarantine, though the fish may have to ingest some of the stuff. The anthelmintics can be absorbed (along with an amazing list of other good and bad things) through the gills. The Metronidazole (despite sounding similar) is an antibiotic and while it isn't as hard on the nitrogen cycle as some antibiotics I would prefer to not use it in an aquarium which has "cycled" and is efficiently breaking down fish wastes.

Parziquantel is also available from commercial sources as Prazi-Pro. 1 Oz (73251 - treats 120 gallons).
http://www.uskoi.com/prazipro.htm

Also at:
U.S. Koi Sales
2804 McCone Avenue
Hayward,  CA  94545
(800) 621-5619

I wonder if Prazi-Pro would also be locally available through pond supply stores.

A couple of other sources:
http://revivalanimal.com/product.asp?pn=78-730&ss=Praziquantel

Fish Tapes Regular contains 34mg Praziquantel per capsule
Regular, 5ct @ $7.99

http://inkmkr.com/Fish/ItemsForSale.html

“Flubendazole Eliminate Carbon filtration during treatment. Change most of the water after 10 days. Will not harm plants, may kill many snails.

Treats protozoa wasting disease, serious treatment for Velvet, internal and external parasites, half gram treats 10 gallons of water for most parasitic Protozoa. ........
$10.00 for packet of 10 grams, plus postage.
Usually about $13.50”

Burgess, Bailey and Excell, in A-Z of Tropical Fish Diseases and Health Problems suggest that the vast majority of flashing cases are because of high levels of nitrogenous wastes. Gravel vacuuming may also get ride of a number of free swimming (commuting) parasites.

Leave the gravel vacuum outside overnight and under the summer sun after really rinsing it in the laundry sink. I was going to say rinse in the bathtub, but that may bother your family. ;)

Other signs of flukes, in addition to the flashing and scratching, include labored breathing, "hyper-production" of mucus on the gills, gasping, coughing, and eventually clamping of fins and loss of appetite. When they don't get enough oxygen, Hypoxia can also set in with yet more drastic symptoms.

For more on gills flukes Google or scan the books  for Dactylogyrus and Monogenetic flukes.

Several treatments, including the anthelmintic Praziquantel were suggested.

"Monogenetic flukes are flatworms that are usually found as ectoparasites of fish. They often have a hooked attachment organ and they have a simple, direct life cycle. They are just visible to the naked eye. They often feed on skin and gill tissue, but usually only cause problems if found in large numbers. Gyrodactylus lives on the skin, fins and gills of many species of fish. This fluke gives birth to live young (others lay eggs). Clinical signs are "flashing" and skin problems. Treatment with formalin, Praziquantel, TrichlorofonTM (dimethyl phosphate) [an organophosphate and not real safe around people - unc.] or salt baths are effective. Formaldehyde is used as a bath for 12-24 hours at 20-25 ppm (mg/L), repeated every three days, for three treatments (same as for ich), with 30-70% water change in between treatments. [ Formalin or Formaldehyde is also a carcinogen. If you must use it, try not and touch it or breath it - unc.] Praziquantel is dosed as a bath for 3-6 hours, at 5-10 mg/L, repeated three times, with 30-70% water change between treatments. Praziquantel is now available in several commercially prepared tablets. TrichlorofonTM is used as a bath, for one hour, 0.25-1.0 ppm, repeated daily for three days, with 30-70% water change between treatments. Salt is used as a bath, as a 4-5 minute dip dosed at 30-35 g/L, repeated daily for three treatments, with a 30-70 % water change in between treatments."

http://www.exoticpetvet.net/aqua/parasites.html