sounds terrible and i'm so sorry for what you are experiencing. we've got to brainstorm and come up w some ideas for you.
may i suggest keeping a diary of what you eat, when intubate, activity, pain level and what ever else you think might be influencing the pain? try it for a week. you know your body better than the doc, they should be able to take the info and figure out what is happening.
has SIBO been ruled out, and pouchitis for that matter? both can cause pain, especially sibo. but i don't know why the pain would then be in your rectal area.
have you had a pouch gram? not certain what it might show. can they tell with a mri if the pouch has attached to another organ? i'll keep thinking about past procedures that i've had.
that said, adhesions can cause extensive pain.
stay strong, janet