My grandson has always had this sticky, almost clay-like stool, and which he struggles to pass. He s 3 and a half, and won t go poopy on the potty. (I can understand why when I see him on all fours with his eyes watering, his face beet-red, trying to poop). Doctors have said give him more fiber, which my daughter has done, but this doesn t change a thing. Can you advise please.