Bleeding off schedule.

Catherine
I wanted to see if anyone has ever experienced the same situation I'm going through right now. 
I just had my period two weeks ago, the usual 3 days and no complaints. 
I'm on the pill, which makes them short and light. 
I had sex about a week ago Sunday, which was pretty rough and we were in a few positions that hurt pretty bad. My cervix is super sensitive so I can't be in most positions because it causes me a lot of pain. 
I started bleeding pretty heavily this past Saturday, it's also accompanied by severe cramps, which is very out of character for my body. 
So I'm wondering what is happening. I don't feel like going through all the steps to make it into my gyno because he's so busy. 
But I'm about to resort to that step. 
Has this ever happened to anyone else? I'm still bleeding as of today with cramps and back pain. 
The blood is a mix of seriously bright red and brownish . Not like the normal period blood I experience. 
Any help would be great!