I agree with the last poster, but also the bag could have scratched. That just sounds painful. I wouldn't recommend using a scratchy ziploc bag down there. If you're worried about germs from your brush, use a condom on it or just rinse it off. I wouldn't worry about the bleeding unless it gets heavier and you experience serious cramping. Don't worry, if you've never had sex, you're probably just not used to having much in there, and it can cause some bleeding.
you might have devirginised yourself doing that. The first time I had a penetration I bled. Which means the tissue that make you a virgin tore. I'd consult a doctor cause it was an object rather than human just to be in the safe side. Hope it helps