Yes, he sounds very young, but it also sounds like he is still very unsettled in his new enviroment. I'm sure he's very scared, not knowing that this is his new home. Just offer him the same foods he is used to, and watch him carefully. Talk to him a lot in a soothing voice, and he should come around once he feels comfortable. That can take a while at first. Definitely keep an eye on his weight, he will drop some, but his appetite should pick up soon. Please keep us posted. You did a very wonderful thing in taking him home. I'm sure you'll give him all the love and care he needs!