I don't know much about diverticulosis and the medicines flagyl and cipro, or if having diverticulosis is a contributing factor to leaky gut (my intuition tells me "no" though) here's my two cents on your comment about being sensitive to rye, barley, wheat and oats. Have you been tested for celiac/gluten intolerance? Since you are sensitive to three grains that are inherently glutenous (oats are not but sometimes rogue wheat can grow in the same field that oats are growing if wheat crops are rotated with oat crops on the same piece of land--you can find gluten free oats grown from dedicated oats fields), I think it would be to your benefit to consider gluten intolerance/celiac testing. People who have gluten intolerance and are still eating gluten, even in the smallest amounts, will have a difficult time trying to heal up their intestines b/c gluten triggers so much damage to the intestines by the immune system. Sadly, gluten is in a lot of things you would never suspect and if you have gluten intolerance and/or celiac its a change in lifestyle in a major way because to regain your intestinal health you have to be vigilant about not consuming any gluten whatsoever. Please check out enterolab.com.