It happened more when I was little but now it's maybe every 2 months it occurs. I'll either stretch or just even shift my position a little bit and the super sharp pain shoots through me as the "string" is getting pulled. The pain usually lasts for a little while afterwards every time I move. Sometimes the pain will continue happening while I am urinating as well. I tried to describe it to my doctor one time when I was younger but they just said it was a bladder infection even though it was not. I've heard some people say it has to do with either your kidney or bladder like either stones or an infection or bacteria or something like that.