Hey, what are his temps now and what are you measuring them with? I would have his basking temp around 110-115 if he isn't eating. Raising the temps should help him along. Warm soaks daily.
What live food are you offering and what are you dusting it with? Try holding a dusted cricket in front of his face. What type of UVB do you have on him? What size is the cage?
Here is my current rescue. She was totally blue from being kept on sand and had also been burmated for a while (not intentionally, though). She's ten months old, really tiny! She's eating like a pig now and her whole head shed yesterday. I've only had her for...two weeks now?
Can you post some pictures of him and your set up?