It sounds like (1) you may be gluten-intolerant (see Sue's reply), and would be best off without grains until you've healed the intestines; (2) you may be allergic to one or more grain or bean items, or even other foods which are being slowed in transit due to ingesting more starch foods; (3) you may be a subtype such as nonsecretor and/or A2, and small amounts of the demon CORN may be continuing to inflame your tissues.

Maybe you don't have a physician who uses these diets therapeutically, in conjunction with a knowledge of homeopathics and herbs, so in your case may I suggest (and I am NOT a doctor! ;-)) using a food diary to record what you eat and your reactions; and start from a diet of allowed vegetables, fruit and fish & meats -- few beans and no grains -- see if it provides improvements, and work from there. You may not have to eliminate them forever, but right now you're in crisis and need special care in choosing foods.

Also ~ a REALLY important part of the plan is release of stored stress, through meditation, yoga, any practice you can do at least once per day (twice is ideal), because colitis, IBS, a number of intestinal dysfunctions are closely related to a persistent state of "fight-or-flight" and accompanying high cortisol in the tissues. This may be true even if you don't feel particularly stressed.

hope this helps!!!