Hi thanks for posting your question.
The commonest causes of bleeding during sex
or after sex is cervicitis
( inflammation of cervix), cervical polyp
and finally uterine fibroids.All these condition require examination by a gynaecologist to establish the diagnosis.I would suggest you to get yourself examined by a gynaecologist,who may be able to tell you what is the exact cause of bleeding during sexual intercourse.
Hope this answers your question.