Eosinophilic Gastroenteritis in Dogs | Stomach Inflammation | Diarrhea in Dogs | petMD
Merck Veterinary Manual
First, if it is IBD, a dietary change may help. So, what are you feeding? This could be caused by an intolerance to a food. IBD in my cat is from some mystery ingredient in kibble and supplements. A raw diet solved the problem.
Second, you need to get rid of the inflammation in the gut which starts with soothing the gut. Are you feeding probiotics? Digestive enzymes? Giving any slippery elm to coat his stomach?
Was any bloodwork done? Xrays for blockages?