Please try not to give hime too many different foods. This is very hard on their tummies, and can cause diarrrea, and make him very ill. I understand your concerns about him not eating as well.
A call to the vet could help you and give more suggestions.
I did give my pup white chicken meat the first day she was with me. She would not eat much either cause she was so stressed out. But, ate the chicken well.
