Taking Methenamine. Coincidentally or not, I have developed an intolerance to certain foods: cabbage or any veggie in the cabbage family; tomatoes, like in spaghetti sauce. I get horrible abdominal cramps that last for hours. Then the explosive diarrhea, which also can last for hours. Have I very suddenly developed an intolerance for certain foods?, Is it the Methenamine?, Or a combination of both? Just found out I need to pay right now to get opinion/advice. No can do. Poop!!