To determine whether the blood coming out of the vagina after rubbing is menstrual blood for menstruation, you can judge by the color and the amount of bleeding. If the blood that comes out is dark red and sticky, some of it is still clots, sometimes accompanied by some non-pungent odor, and the bleeding happens to be at the time when you should normally have your period, then it may be menstrual blood. In addition, the menstrual cycle is continuous and its bleeding will be heavy. If the vaginal bleeding is caused by rubbing, it may be due to a ruptured hymen or localized rupture. The blood should be bright red, not sticky, less in volume, not persistent, and odorless.