I’ll also throw out a suggestion to look into the specific carbohydrate diet (also called the SCD diet) - it was designed by the doctor who discovered celiac disease but it was for people suffering from colon problems like ulcerative colitis and crohns. Essentially, all complex carbohydrates are out so one eats only meat and vegetables. It’s a diet that is extremely easy on the colon- allowing it to heal and absorb nutrients easily and not feed the bad bacteria. Combined with a strong probiotic, it can help alleviate colon problems- even auto immune ones like ulcerative colitis and crohn’s. I used both approaches with my son (as well as an organic diet without gmos). Good luck - chronic pain is a terrible way to live.