Ask your doctor whether you don't have a retroverted uterus as chronic lower abdominal pain could be related as well as the pain during sex is a common symptom.
you suggested to mousy that she could have a cyst on her ovary, I had the same symptoms she did and had my ovaries removed with the falopian tubes also removed... that was months ago and I still have the pain in my right lower side...it's worse after sex.
Could be a cyst on your left overie.