WHY?!??

I’m losing my patience... honestly so fed up and over this. Why is my almost 4 year old not listening to me?? It’s come to the point that he holds in his pee and pisses himself! This was never an issue. He was potty trained at age 2 1/2 and was never forced. He learned on his own day by day and now he’s just not going until he pisses himself. I already tried leaving him in the clothes till he’s uncomfortable, it won’t work. He knows where the bathrooms are at. He knows how to turn open the door and turn on the lights and either stand or sit on the toilet. The toilets aren’t tall. As a matter of fact, he’s pretty tall for his age so that’s not even the issue! He’s not afraid of the toilet or bathroom either. Ever since he started being babysat he started having accidents on the daily. I would ask him if his babysitter takes him to the bathroom or what and he doesn’t tell me anything🤦🏽‍♀️. She doesn’t watch him anymore so she’s not the issue anymore if that was the case. Yesterday I got so upset. I bought him his Halloween costume to go to the fair and after putting it all together and showering him and changing him into it.. I walk away for a second and come back and he tells me he went pee in it.. I just.. I can’t no more. I DON’T KNOW WHAT TO DO ANYMORE. I DONT KNOW WHAT TO DO WITH HIM. I’ve tried explaining to him millions of times that his pee needs to go down the toilet. That he shouldn’t be peeing himself. At times he’ll even just dance around and will catch him and tell him to go to the bathroom and he goes and still dances in there till he pees himself!!! 🤦🏽‍♀️🤦🏽‍♀️ I just don’t understand.