What Causes Bleeding During And After Intercourse Following Total Hysterectomy?

Hi I had a total hysterectomy 3 months ago(keeping one overy) to help with my endometriosis, all went well until last week i had bleeding during and after intercourse. went to the dr 2 days later and was given an internal but was told he could not see were the blood is coming from as there was too much to see. I was given 2 lots of antibiotics and swabs were taken. however i still dont know the cause, the bleeding has stopped but i still have abdominal pains and tenderness? My gp could not give me an answer as to what it could be? any help would be great.

thanks