Thank you for getting back to me. Turtles are more difficult to care for than most people would expect. They also can be expensive to get started with. They can live 30 years or more, when properly cared for. To complicate matters, pet stores often give out incorrect information on care, and then, well-meaning pet owners do not know what is best for their pets. I suspect this is what has happened to your family. It's not your fault, and I can tell you care about the turtle, but if you want to return it to health, there are some important changes you'll need to make. I'll start with care, then, we'll talk about the turtle's problems.
Your container is way too small. It's recommended that a baby turtle have at least a 15 gallon tank. By the time the turtle is 3-4 years old, it will need a 60 gallon tank, so it's best to get the biggest you can in the beginning. You can also use a large RubberMaid tote. That's not as pretty as a tank, but costs a lot less. Set up the tank so there's a land area and a water area. You want the water to be about twice as deep as the turtle is long. If the turtle is two inches long, you'll want four inches of water.
In order to have healthy skin and shells, 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, with the basking area 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. Hardware stores sell similar fixtures as work lights. The basking area should be kept at 85-90 degrees (29 to 32*C). Use a digital thermometer to be sure. You can adjust the temperature by raising or lowering the light fixture. In a small tank, set up the basking area at one end - you don't want the entire tank to become too warm. The lights that come with the covers on aquariums are not suitable for turtles. 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. A Reptisun 10 is a good brand that does. 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, or UVA are not the same thing. I'm putting a lot of emphasis on this because it's crucial to your turtle's health. Without this light, Metabolic Bone Disease (MBD) will develop because your turtle 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 only 1/4 of the diet. Animal products (cooked meat, earthworms, canned cat food) should make up another 1/4. The remaining half should be plant foods (dark greens, bits of strawberry or melon, etc.).You may want to look at these sites for additional information on care and feeding.http://www.austinsturtlepage.com/Care/caresheet-eastern_painted.htm
At this point, your turtle is suffering from a condition called shell rot, and probably also from MBD. It's urgent that you provide proper lighting and temperatures as quickly as possible. Once everything is right in your set-up, you'll be ready to help your turtle get well. The best thing you can do is take him to a reptile vet. Depending on what stage the illnesses are in, the turtle could need an injection of calcium, antibiotics, debridement of the shell, or other treatments only a vet can provide. This link will take you to a directory of reptile vets:http://www.anapsid.org/vets/index.html#vetlist
Some turtle owners do attempt treatment of shell rot on their own. It's fairly complicated and has a number of steps. For that reason, I won't give you details in this post. Here are two sites that give step-by-step instructions. They're different, so you can look at both of them and choose the one that you prefer.
If you try this, and don’t get results within a week, you’ll need to see a vet.
Sometimes families get a pet turtle without knowing about the equipment and care required. With the economy the way it is, the expense may be too much. If your family is in this position, give me your state, and I can refer you to reptile rescue groups who would take the turtle and care for it. Most families feel that is better than simply letting the turtle die. I hope this isn't your situation, but if you want to look into this option, don't hesitate to let me know.
If you have further questions, or want a list of rescues, just let me know by clicking on REPLY. There's no additional fee for such follow-up questions, and I'm happy to help. I hope you enjoy many years with your turtle.