Pain in Lower Left to middle abdomen

I had a total colectomy 6 years ago with ileo anastomosis due to diffuse gastroentestinal motility disorder which caused substantial nausea, vomiting.  For the last year I have been well.  2 days ago I began experiencing lower left to middle abdominal pain which seems to be worse when I walk with what feels like a heavy pressure.    When I sit down, the pain radiates up the rectal area.  It sometimes feels like pressure against the bladder also.  Nothing seems to relieve the pain i.e. not urinating or having bowel movements.  Bowel movements are consistent with someone who has had a colectomy.   There is no bloating or gas.  Anyone who has experienced this type of situation, I would be happy to hear from