Why am i bleeding during sex? does being on birthcontroll gave anything to do with it?

me and my boyfriend had sex and he got blood on his shirt from me i guess, this is the second time this has happened. i just don't get it. . i'm on birth controll does that make you have spotting? i'm also not a virgin. so it can't be my cherry getting popped or whatever. i need a solution to this problem help me out pls . :\