My male leopard gecko very sick not eating.. new help! whats going on with him?

I have a 9 month old leopard gecko male! i bought him from horrible breeders from a reptile convention that were just trying to get rid of there baby geckos(i had no idea of it until now)! anyways Ive had problems with him from the start.. Bone deficiency, and he had to get one of his hemies removed because it fell out and dried up! he was doing great after that surgery! But now hes very very sick i took him to the vet and all she did was tell me to force feed him with dogfood/baby food (she even admitted she didnt know what was wrong with him.. waste of 70 dollars) which what i have been doing 3 times a day. His symptoms are Hes very very weak and he cannot keep his eyes open for more then a minute he has them closed alll day and all night! he doesnt play or run around like he used to! He only lays around in his peatmoss hhut alll day and night he doesnt go in any other hides..he hasnt pooped or peed in a long time! and he has lost half of his body weight.. im soo afraid on the outcome from this! i just want him to get better ! PLEASE if anyone has any idea on whats wrong with him let me know!! i just wanna save my little guy before its too late