I have been on my period for 3 months?!?! What could be wrong?

I got on the shot in February. At the end of the month I started bleeding. In May my doctor put me on some hormone pills to stop the bleeding, didn't stop. So then she put me on the pill, haven't stopped for almost 3 weeks. I have been bleeding worse for a couple weeks and the cramps are unbearable. What's wrong with me?