Have you gotten away from meat entirely yet? I would recommend trying a very hypoallergenic whitefish based diet (Marcel's nutiritionist recommends this) - it can be a MIRACLE, especially for dogs who are in real trouble, and it sounds like yours is in that situation.
It is not a long term diet - but it is def. fine for 4-8 weeks (even longer w/ proper supplementing, if it's all he can eat). It's whitefish (pollock, tilapia, whiting, cod, sole, trout, etc), mashed potato, steamed/pureed green bean.
You'll need to portion it correctly and supplement w/ calcium - what is his weight? And, are you willing to cook this for him, then?
***And, I should add - I really think you should consult an actual nutritionist asap...the one I used was
www.askariel.com, but there are others as well out there.
