Okay... Do you know ensure shakes are okay for you? because high on the list of the ingredients are maltodextrin - a synthetic sugar, and milk proteins. Maltodextrin is supposedly well tolerated, but I suspect it isn't reading between the lines of many peoples responses to Ensure, Modulen and Elemental 028. Dairy is a known problem area too and it's not just lactose, the milk sugar, that is the root cause. If I drunk any of them I'd be out of remission in a shot - that's not to say it's the same for you!....
So, can you lay off the Ensure for a few days, a week perhaps, stick to rice and chicken, or turkey(!)? see how that goes.