First of all, he's lethargic because he is stressed and his conditions aren't fully supportive. That enclosure is far to small. So by getting him out, and letting him explore, you are causing him more stress at this point just making things worse.... I wouldn't even take him to the vet again honestly because anyone on here will tell you the problem is his enclosure. And another vet visit will just stress him out more. Just leave him alone and give him as much cover in his enclosure as possible and get that larger enclosure asap. What is his diet like? Is he eating? Also not sure what you mean by the greenish tint, they are naturally green?