Bleeding after !! HELP!?

I've recently begun having with my second boyfriend (I am not a virgin- lost it to my first one, and there was no bleeding, but he was a lot "smaller"). I am on birth control Yasmin. The first couple times I didn't bleed after with my new boyfriend, but that past 6 times I've bled (not very heavily) but there is still blood there and it absolutely STINGS to go pee and my is really sore. We haven't really given a break to though. We've used lots of lube too. What's wrong !?