So, I'm 14. Earlier In The Month I Thought I

So, I'm 14. Earlier in the month I thought I had my period but it was just a large amount of drak brown blood for a short time, a couple days. Then this week I've had really bad sharp pains around my uterus, then today I went to the bathroom and there was a mix of brown blood and bright red blood, and my uterus feels kind of like cramps but I'm not sure. I just don't know if I should go to the doctors or not.