thanks for using health care magic.
If your girl friend has never had intercourse before, there is a good chance that the bleeding is a result of rupture of the hymen
which could still be available in part if she has been seeing her menses. This usually is associated with pains and bleeding and could explain her present situation.
However, if she is not a virgin, and that she has had a couple of intercourse, the idea of a hymen rupture is less likely. In this case, other diagnosis will have to be considered such as an infection of the vulva
or the cervix
. More so, a speculum exam in which the genital tract is observed will have to be done to rule out more severe and potentially dangerous causes thus a consultation will be needed.
Best regards and hope this helps you.