How bad does rough sex make you bleed?

I'm a week away from starting my period and me and my boyfriend were having intense for play and when we finally got to business not even 3 minutes later there's blood all over his penis. Not a little blood either. A lot of bright red blood and some chunky clot looking stuff that I normally get with my period. But I'm not supposed to start yet.  I got really bad cramps as soon as I stood up to go shower it off. I had to sit down it hurt so bad. Is this normal? Or is it something else or just my period? The cramps went away right away and now I'm fine. It just doesn't make any sense at all. Help?