Hi i'm having the same problem exactly! I am 15 and my period won't stop, I have had it for like 2 and half weeks now! But, I am on my second round of birth control for irregular periods and I have read that a lot of people have this problem. Tell your parents and go to the doctor or gyno! If you haven't been before it is quite scary and weird feeling, but I am willing to do it to just get this damn period to stop.
Try not to be scared, you are so young that your body is probably still working out its schedule. My guess would be that it will taper off in a day or so. Sometimes an ovarian cyst (not a serious thing) will cause a period to be a little unusual.