My wife has a reoccuring problem where she cramps in the abdomen and pes blood in her stool.Docs are lost.?

She's had CAT scans, scopes done (both top and bottom) and the cramps are always along the left side of her stomach. Diverticulitis has been rulled out and the only thing ever found are some polyps and Diverticulosis with one of the scopes she's had done. Every time she has this and goes to a doctor, none of the tests every suggest what could be causing the problems. She has this happen at most twice a year I think. It does not seem to coincide with her periods either.