My 3yr old son is almost fully potty trained. He still wears a pull-up at night and he is very inconsistent about using the toilet to go poop. He has a very hard time going poop all together. I have changed his diet, limited how much milk he intakes, I ensure that he drinks enough fluids. I don’t know why my son holds his poop. I’m assuming because it was painful before and he doesn’t want it to hurt. I spent all day trying to get him to go poop and he never did. Please advise on what else I can do?