Help!

So this is odd. I got my period august 31st until September 5th. I haven't gotten my period yet. But I've been bleeding a lot during sex (past three times last week/this week). After sex I put a tampon in continue my day, take it out there's absolutely no blood. But when I poop some blood comes out (we don't have anal sex never have before either). This morning I felt a little crampy looked at my underwear a tiny drop of blood was on it (not even red, more like the lightest pink color) put a tampon in, just took it out and NOTHING. What the F is going on with me?!