I had unprotected sex on 15th of this month. Exactly 10 days after, I started bleeding very heavily from my vagina. It was much heavier than any period I ever had. It started off heavy for the first 2 days, then gradually got lighter and stopped. I stopped bleeding today. I started bleeding when it was roughly a week 'til my next period is due. My next period is due on 2nd Feb. I've already had my January period, so I'm very worried as to what this could be. Is it cervix inflammation? Pregnancy implantation failure? An STD? Please, put me out of my misery.