Thank you for writing. If you haven’t already done so, the first thing to do is to make an appointment with your son’s pediatrician. It’s important to rule out the possibility that moving his bowels is hurting him in some way. Also ask the doctor how frequently your son should be pooping. Not all children are on a daily cycle. Not everything is psychological.
That being said, it’s possible that the issue has become a power struggle between you and your son. You say he is a strong-willed, smart kid. Think about it. A child really has little say in life. Most of what he does is dictated by the needs of adults.
A strong kid needs to flex his “will” muscles. Some kids do this with nap refusal. Some become picky eaters. Some tantrum if asked to pick up toys. Your son may have landed on potty pooping as a way to show you that he is in charge of when he’ll poop, not you. Strong willed kids come up with unique ways to frustrate their well-meaning parents by refusing to do something they really need to learn to do. And, being well-meaning, the parents insist.
The child pushes back by continuing the refusal. The adult insists some more or tries 43 different ways to bribe, cajole, punish, reward, the behavior until they are ready to pull their hair out. The kid wins! Except he loses. Some of these power struggles can result in health issues that are serious — like illness from not pooping for days.
I do urge you to talk to the pediatrician, who knows your boy, about how best to break the cycle of refuse-insist-refuse. But here is one idea to run by the doctor.
Since your boy is smart, I do suggest you start by matter of factly admitting to him that you can’t make him go potty unless he wants to. But you can also talk to him calmly about how not going as often as the doctor recommends can make him sick. Tell him you certainly don’t want that to happen because you love him so much. Ask him if he has some ideas about how he can take charge of his own poops. You may be pleasantly surprised to find he does have an idea or two.
The most important factor in making this work is for you to find a way to not let him see your anxiety about it. A whiff of your anxiety or pressure and the fight is on. Talk to him calmly and with caring. Work with him to come up with an idea and then genuinely try it out for as long as is healthy (as recommended by the pediatrician).
Meanwhile, think about other ways he can have some say in his life. Offer more choices. For example: “Would you like juice or milk this morning?” “Do you want to wear the red shirt or blue one?” “Do you want to have your bath before or after dinner?” Only offer choices you can live with but do offer him lots of them. Tell him often what a smart, big boy he is.
The two of you will get through this. A wise woman I know once said she was cursed with having smart kids. Everything was an issue. That curse turned out to be a blessing. Both of her kids learned to use their persistence and strong personalities to become successful adults.
I wish you well.