Thank you for getting back to me, Roland. your turtle is not eating and is inactive because she probably has a respiratory infection. Repeatedly opening the mouth is a classic sign of a respiratory infection. She really is gasping for air. You can't cure this at home. She needs to be on a course of antibiotics, not just one shot. Please don't put anything else in her mouth when she opens it because it can very easily be aspirated into her lungs. That is life-threatening. Vitamins are not going to help anyway. I know you don't want another vet visit, but if you hope to save this turtle, treatment by a competent reptile vet is going to be the only way to do it. This link will take you to a directory of vets:http://www.anapsid.org/vets/index.html#vetlist
In the meantime, you need to get the temperature under the basking light up to 90*F. I can tell you care about your turtles and want them to be healthy, but someone (probably pet store personnel) has given you incorrect information on how to do that. Unless you make some changes, as time passes, you'll see more illnesses and deaths. I can tell that you care about your turtle, and want to take good care of him, but someone has given you bad information on how to do that. If you want your turtle to be healthy and live a long life, there are some important changes you'll need to make. I'll give you a basic summary of slider turtle care, so you can see what needs to be done..
It's recommended that a baby slider have at least a 15 gallon tank. One adult needs at least 60 gallons. Two should have a minimum of 90 gallons. You want the water to be at least twice as deep as the turtle is long. If the turtle is two inches long, you'll want four inches of water.
Turtles need certain types of lighting and need to be warm. Air and water that are not warm enough can lead to fungal and respiratory infections. Turtles must have a basking area where they can get out of the water, dry off, and bask in very warm light. The ambient air temperature in the tank should be around 75 (24*C) degrees, so your ambient air is fine, but the basking area should be warmer still. Over the basking area there should be some sort of lamp that will take a 40-60 watt incandescent bulb (or you can buy a ceramic light fixture made just for reptiles). If you live in an area that has farm stores, you can buy a metal light fixture made to keep baby chicks warm for just a few dollars. Don't buy the accompanying bulb, however. You need an ordinary incandescent bulb in the basking light. The basking area should be kept at 85-90 degrees (29 to 32*C). 90* is better for a sick turtle. Use a thermometer to be sure. You can adjust the temperature by raising or lowering the light fixture. Since your tank is small, set up the basking area at one end - you don't want the entire tank to become too warm. You'll also need a submersible aquarium heater that will keep the water 78-82 degrees (26 to 28*C).
It's extremely important that you buy an additional light that produces UVB rays. Your Turtle Tuff only provides UVA. Turtles need both kinds. Make sure the new light provides UVB rays. A Reptisun 10.0 is a good brand that emits UVB. If you choose another brand be absolutely certain it provides UVB rays. Don't take the word of pet store personnel, but read it for yourself. Full-spectrum, DayGlo, daylight, UV, and UVA are NOT the same thing.I'm putting a lot of emphasis on this because it's crucial to your turtles' health. Without this light, Metabolic Bone Disease (MBD) will develop because your turtles won't be able to produce vitamin D. Vitamin supplements are not a good replacement for the proper lighting. MBD causes a very slow and painful death. UVB bulbs must be replaced every six months as they lose their effectiveness after that, even though they may still look fine. Light that comes through a window isn't sufficient because the glass filters out most of the rays turtles need to stay healthy.
Turtles are very sensitive to water quality. Even if you change the water every day, it can still contain harmful chemicals. A good filtration system is essential. Water changes are also needed even with a filter.
Feeding is another area where pet stores often give out bad information. Commercial food should make up 1/4 of the diet. Animal products (meat, earthworms, canned cat food) should make up another 1/4. The remaining half should be plant foods (dark lettuce like romaine, bits of strawberry or melon, etc.)
You may want to look at this site for additional information on care and feeding:
If you have further questions, just let me know by clicking on REPLY. I hope your turtle will reach a full recovery.