Post cancer bowel management

Hi, I'm a fellow nurse asking for peer help! My son had colon cancer 1.5 years ago. Surgery successful. Problem: he stools mucus, 'rabbit poos" and some thin stools 10-12 times a day. Has to wear an adult diaper and can't eat unless he wants to be up all night on the toilet. Sense of urgency common.
His surgeon treated for a stricture last year. (no change or help). (Radiation and chemo complete a year ago).
We need to find a multidisciplinary team of specialists who can help him to diagnose and correct his stool problem. Who or what do we look for? Will most GI doctors have a team that can help him?
He is 44 year old, living in Chicago. (We will go anywhere at this point, tho!)