Hi. First of all , I would request you to enlist the problems, surgeries in a good chronological way for me to understand what exactly is the history.
Since you are giving a history of
Colitis,
IBS and Barretts, I wonder these to be one of the important causes of the pain you have.
I would advise you to have few investigations.
Please ask for a Enteroclysis wherein you are given barium through a nasogastric tune to delineate the bowel in real-time to see what exactly is the motility, any obstructions , strictures and so on.
Now-a-days camera
endoscopy is also available.
You can go for diagnostic
Laparoscopy to see exactly the interior of the abdomen.
I hope these tests would help you to get a proper diagnosis.
Constipation has to be avoided at any cost as these will enhance the problems.
I hope this will help you.
Please post previous records.