When my Lab's tumor ruptured on her leg, the Vet was very concerned that she would get depressed before we made up our mind on what to do. She was worried that she would feel down if she didn't get exercise. So, I took her for short walks each day just so she would get fresh air and smell the bushes and poles.
Is it okay for your dog to take walks? Does he get one every day? You might ask the Vet if he needs exercise. It may be that if he is sitting around the house too much he's getting bored and feels down.
Let us know how it goes Monday. I wouldn't change anything or add anything to his diet until you see the Vet--and maybe get a second opinion, too. You don't want to make matters worse by adding stomach upset to the list.
