PWT here! When my little one was going through cancer last year, we would entice her to eat by feeding her McDonalds burgers with cheese and bacon. Worked like a charm. Hot dogs for more than a day or two would back her up, if you know what I mean (she was only 6 lbs). Have you considered making his food? There are great healthy recipies on the internet, and it doesn't have to be the raw food kind.