My guy is the exact same way. The tripe solved our problems until he got tired of it. I figured out that he just likes variety so I feed him the same kibble but buy 5 different flavours of wet food and mix with his food. We buy fish, herring, turkey, lamb, and tripe. Once he finishes one can we move onto the next.
My husband says I'm spoiling him but whenever I called the dog's bluff he refused to eat for two weeks and lost 4 pounds. I worked so hard to put that weight on him due to his digestive issues that I'm not willing to let him lose it over something that I can easily solve.
Jazz, Shiloh Shepherd, 5 yrs old, CGC HIC
Bunny, GSD X, 7.5 years old