Your dog is probably suffering from food allergies. This is an all too common problem caused by commercial foods that contain cheap fillers like wheat, barley, sweet potatoes, etc. Search your area for limited ingredient canned foods of Lamb, beef, Rabbit, or fish. Most Vets do not understand the significance of this but, there are some out there. I am not affiliated with this site but we use it as a reference and it's very helpful: www.dogfoodadvisor.com. Good luck to you and your little friend!