Ok. To start off, I don't take any birth control, I'm not on any type of any sort of pills either. I'm 17, but I'm bleeding twice a month. This started happening out of the blue around August. I'll bleed for one week, but my blood comes out like red water or mucus and can only be held by a tampon.(it won't stay on the pad) It then stops for another week but this time, it's actually thick, normal blood. What is going on??