A raw diet is not a bad idea.
However, finding a high quality kibble is also not a bad idea...if you're offering him food made mostly or entirely of meat, he may not be eating it because he's filling up on junk food like biscuits and treats. A small dog doesn't need very many bones or treats to fill him up.
I would cut back on the treats and make sure the food you're feeding is high quality, healthy food, and see if that helps.