I was doing potty training with my 3.5 year old DS. Within three days he'd cracked it, then a week later suddenly decided he doesn't want to poo in the potty anymore! He wees just fine (hasn't had a wee accident in weeks) but will poo in his underpants right next to his potty despite knowing what to do. He seems afraid of using his potty to poo. His butt isn't sore, and we've tried bribes, and withholding favourite toys. Has anyone dealt with this? Any tips?