For the last 6 months or so I occasionally (about once every two weeks sometimes more) get woken up by a pain in my lower stomach/back.  I can't pinpoint exactly where the pain is coming from, but I know it is related to my bowel.  It feels very crampy (kind of like a period pain and constipation) and it brings me out in a cold sweat.  I have to take strong painkillers for it to go away and for me to be able to go back to sleep.  My somtach feels tender the next day.  This only happens at night.  Has anyone else had this problem?  If so, what was the cause?  I have suffered with constipation before, but it didn't feel like this.  I also had a burst appendix about 6 years ago which was operated on, but I don't think it's related.