What Causes Endometriosis?

today i went for usg of pelvis as suggested by doctor.i have the problem of endometriosis.today the radiologist ask me if i have gone through any hormonal test.i have physical relationship with my boyfriend.is there anything to worry about?i was having meprate10 twice a day for last 3 months as per doctor's advice.my menstruation started on 17th march and the medicine was stopped on 14th.