My two-year-old son started potty training (because of his own interest) when he was 20 months old. He was really good at it for six months, but now won't go near the bathroom and now he poops especially during naptime. How do I get him to use the toilet again?
As difficult as this is to hear, give potty training a break for a month or two. Your son will learn to use the toilet, but it might not be for another three to four months. It's difficult when a child looks like he's on the road to potty training but then regresses, but it happens. He'll get back on track, but not if you pressure him.
Have him sit on the potty before his nap, but if he doesn't go, so be it. You can't control whether he does or not, all you can control is giving him the opportunity to try.