Some people do get relief with Questran (cholestyramine), which binds bile acids, so it might be worth a try. It comes in sugar-sweetened and artificially sweetened (Questran Light) forms. It may firm up the stool, so use it carefully. It also binds many, many medications and has to be timed well away from them.
Have you tried biofeedback or pelvic floor physical therapy? These can be quite useful to some in dealing with a dysfunctional pouch.