Cindy S-
My dogs love tripe as well. I notice that you feed canned Tripett by Petkind. Their canned tripe has carrageenan in it. Many dogs (including mind) seem to be sensitive to this ingredient. K9 Naturals sells both frozen and freeze dried tripe that does not contain carrageenan and it works much better for my dogs. They also have sensitive stomachs.
But, yes, Pitlove is correct, it could be more than a sensitive stomach and you may want to see a vet and/or at least bring in a stool sample to be tested.
Good luck!
