What Causes Heavy Bleeding In Between Periods?

I am a 22 year old female and I get regular periods each month. A day ago, I started bleeding very heavily in the morning and it eventually tapered off. I was again bleeding heavily this morning. I have never had bleeding in-between my periods like this before and my periods have never been as heavy as the bleeding I am having now. I am supposed to be ovulating right now, so I am wondering what is wrong.