According to the symptoms you provided, you might be experiencing vaginal bleeding after intercourse due to endometriosis. Endometriosis is a condition when the normal lining of the uterus is found on other organs. It has the same histological structure. When found on the surface of the ovaries it can help ovarian cysts to appear. When found on the vagina wall or cervix, it is more susceptible to trauma than the rest of the vagina.
You might want to visit your gynecologist to exclude other reasons for vaginal bleeding after intercourse: Chlamydia and gonorrhea, cervical or uterine polyps, cervical dysplasia, for example.