What Causes Lower Abdominal Pain?

Hi I have been having lower abdominal pain for awhile now . but this pass couple of weeks it has been worse. it goes across my lower abdomen especially when I have to have a bowel movement, after that its not so bad, but its still there. worse at times than others. my bladder is down and causing pressure and the mesh that was there to keep it up has been out of place for a long time. I would like to know what could be causing the pain. I am a female.