I am having a lot of trouble with my 3-and-a-half-year-old and the potty. He started using the potty regularly a little before he turned 3-years-old and, although he wasn’t wearing underwear, he had a good handle on when he had to go. After four months of this, he started having accidents all the time. Now he goes a week or two without accidents but then he has accidents every day for three weeks. I don’t understand why this is happening.
There are several reasons for toilet training failures. There are kids who get so busy with what they are doing that they don't pay attention to the urge to go--until it is too late. There are kids who do well at home but hate public potties, so they hold it at preschool or when they are out and about. Some kids have real fears about the potty or have had a bad experience where it hurt to poop, so they avoid going when they really need to. Without having full details of what your child has gone through, it is hard to say why he is unsuccessful. But, I believe that underwear is a privilege and not a right--meaning, if he has accidents this often, he is not officially toilet trained, so he needs to remain in diapers until he is truly ready.