I think you might get better answers if you ask this to be moved to Health and Nutrition Forum but I did do a little looking around on Google. Most of the articles suggested food allergies (corn or wheat), parasites or feeding table scraps or cheap food. They all suggested a vet visit. I really think that he needs to go back to the vet to make sure that he does not have any additional parasites still lurking around in his intestines. Then I would start ruling out food allergies. I hope you can get some better answers as I am just guessing.
