Yorkies are so sensitive to food. Chibi had tummy problems for the longest time. Every dog is different. But we found that EVO Innova was good for him. Some little ones have allergies to wheat or other grains, so we tried this food and it seemed to work. Although since it is high protien we add potato, since it's easy to digest. It seems that dogs have difficulty digesting starch such as corn. Our vet suggested allergies. Vets are helpful here, I know in the U.S. it is hit-and-miss with vets. Good luck, sorry if I haven't been much help. We hope Duncan can feel genki (healthy) soon! Sending Yorkie kisses!