It wasn't her first time was it? When you say she started bleeding, was it spotting or just like her period and she's still bleeding? I know that if your period is close and you have sex, especially with orgasm (it causes the uterus to contract just like when it's trying to expel menstrual blood) it can bring on your period but her period is like 2 1/2 weeks away. Has your friend calculated her cycle properly to the 10th September?
well or uhm her boyfriend and the person you ****** with might have streched your vagina.. it happend to me??
maybe her boy friend fuked her to hard