Cramping

So, I don't have periods I stopped having them almost as soon as I started getting them and the only way I'm able to have a period is with help of birth control pills. I stopped taking them two years ago because of awful side affects and haven't had a period since. For the past week I have had terrible cramping pain that comes and goes when I walk or am more active in general the cramping gets worse so I thought MAYBE I was trying to get a period even though that would be odd for me, but I STILL haven't had any bleeding, spotting nothing. What could be wrong?