Most of the pain that I experienced was from gas pain. It was very painful at times, particularly the first 2 or 3 days after surgery.
Every time I saw a nurse I was asked if I had passed gas. Had no idea gas could hurt like that, but it sure did. Was told that the openness of the surgery leads to air being captured when the patient is sewed up.
Not sure if this is the problem you are experiencing, but thought I would share.