I Have had my period for 13 days now!!! and I'm starting to wonder if if I should go to the doctor??? I had HORRIBLE pms with it and can't stop itching! I'm on Yaz, but it's not helping. What to do???

I can't tell you for absolute sure, but I had this same problem happen to me when I was about 16 years old. I was on Depo birth control, and, at first it seemed to be working just fine for me, and everything was normal, but about a year into being on Depo, I started having my period for a couple weeks at a time. I went to the doctor and it was the birth control that was causing it.....
I think you should go to your doctor and discuss everything thats going on, maybe you need to be on a different kind of birth control.
Good luck!