What brands of food have tried? We went through this with our when we first got her, always liquid poop! It is very frustrating. We took her to the vet it it all checked out ok. We tried 4 different foods. I was on here one day reading and someone mentioned giving their dog Pedigree and had solid poops. So we tried it and she had has had solid poops ever since. I know its not the standard food to give a grey, but out vet had no problem with us doing it. She has the same amount of energy as she did on the high end foods. It sounds like you just need to find something that is gonna work for him.