Intercourse can cause bleeding
especially if it is rough, or if it is there is inadequate lubrication. If you've been bleeding for a week, I wonder if you have just gotten your period. Much of the time, unexplained vaginal bleeding is just blood coming from the uterus because of menstrual flow. If you stop bleeding here in the next couple days, that is most likely what it was. Another possibility is that you broke some blood vessels in your cervix. The cervix contains a lot of blood vessels that can easily break especially after rough sex. The blood is usually minimal, and usually doesn't last more than 1 or 2 days. Finally, sometimes you can bleed a little from the vaginal wall after sex. However, this usually only happens when there is inadequate lubrication and the bleeding is typically painful. Again, it usually doesn't last more than a day.
I suggest that you schedule an appointment with your OBGYN. He or she can take a more detailed account of your bleeding a perform a pelvic exam to determine where the bleeding is coming from. If the bleeding is coming from your cervix or vagina, then your doctor
will want to do some blood tests to make sure that your blood clot forming ability is intact. Good luck.