Another thing that would go straight to my Colon and cause immediate pain was the sugar free sweaters in See's candy. It took several painful experiments to prove this to myself.

At my sickest I would also experience immediate pain from anything with heat in it. Hot sauce, horseradish, chili peppers, jalapanio etc. I also used myself as a guinea pig to prove it to myself.
Raw veggies of all types, I completely stopped. 95%+- of it ends up in the Colon undigested, (read fiber menace to learn why)

While healing I ate a lot of pots of homemade chicken soup with no veggies, then later some onions very well cooked, celery came much later after I healed more.

The veggies I handle very well now are yellow squash and zucchini, well cooked.