My 3yr ds just started using the toilet and wearing underwear last week. It was motivated on his part....I've been encouraging him, but he's the one who really wanted it. He's doing very well peeing. However, he's frantic when he has to poop!! I offer to sit with him next to the little potty or hold his hand while he sits on the big potty, but he refuses. I've been putting a diaper on him and letting him poop in that. I'm not sure how to proceed. Any ideas????