That's horrible! I'm so sorry you are going through this. I have had instances of diarrhoea but only very few. I have heard that some people can be intolerant of lactose and sugars and fats after surgery and that it will improve over time. The fake sugars in the sugar free foods can give you the runs also, so maybe you are sensitive to them too. i would call your surgeon and or your dietician and ask for advise. I know having fiber like benefiber can give bulk to you poop so it's not runny. I would ask my doctor though. I really hope you feel better soon.