So I'm 21 and I lost my virginity on Monday and since then I've had sex 3 more times. After this last time I woke up the next day bleeding a bit. I mean the sex wasn't rough but I my body was sore the next day. It isn't my period because I had it last week. I thought it was my birth control messing up but I'm not sure.  now it's a little heavier and dark red-brown. Is this normal and when will it stop? I'm a little concerned.