What Is The Cause Of Heavy Bleeding?

Since November 18 I have been bleeding more than not. I went to the local ER and was prescribed a medicine to stop the bleeding for 10 days and it works except after sex. I bleed the night of or the day after sex. This has happened every time since all the bleeding began. I had an abnormal pap in July of this year and my next pap is scheduled for Jan 9. I have a long family history of cervical and ovarian cancer. Should I be worried?