Aww Michelle I am so sorry, I know how our fur babies worry us.
I'm trying to think of things that he may eat - my 2 girls are mega fussy. How about trying some of that meat that is in a bit "sausage" type thing. Do you know what I mean? I always think it smells really nice and my girls will eat it too, that and Forthglade.
I tend to feed them whatever I am eating too.
I hope things get easier for you.