issues abound here! He might have a sensitivity to something in the food. Yes..food and parasites are big triggers of runny poo. Has he been tested for parasites and Gardia? You can always add a spoonful of canned pumpkin...not the pie filling...to his food. It works great..but if it continues..you might consider a food switch..or allergy testing to narrow down his sensitivities. They can do fine on a food and then start to have problems. Kind of like it takes their systems time to show allergies.. very confusing!