FWIW....I see a lot of folks suggesting chicken. A few weeks ago I posted a problem with our 10-11 year old Pit Bull losing weight, had diarrhea and rumbling gas. The Vet thought maybe a chicken allergy. It seemed too simple of a remedy for the problem but I made the change. I was feeding Blue Buffalo,(chicken) with a little boiled chicken mixed in. The Vet gave him a ten day medication for the diarrhea and I switched to Basic Balanced Diet, sweet potato & bison and stopped all chicken. So far he's gaining back the weight and no more diarrhea. I hope it continues. The stomach rumblings in the Rottweiler had also stopped. Will take him back next week for a check up.........
.......For what it's worth.... Good luck..