If it hurts and bleeds abnormally much I suggest you see a doctor, but otherwise don't worry too much. If you have rough sex sometimes you rip a bit of the skin/uterus wall. It should heal up pretty quickly. As for the abdomenal pains you have, officersangel, that's maybe because he went a little too deep. When he hits your cervix, it causes low abdomenal pain. Nothing to worry about too much, but if you are I suggest you see a doc :)
I am going through the same thing, But I have pain in the left side of my abdomen with the light tinged bleeding...I'm totally freaking out!
It could be many things, probably just from the sex. But your health is not worth not seeing a Dr. You can wait and if you continue to bleed then you have to see a Dr.