After 11 years RNY I have now been advised I am pre diabetic with much the same symptoms as you.
I struggle with eating out where alcohol is involved, parties & Christmas are a nightmare for me. I find myself having to go lay down until the spike episode passes.
Tonigh I had a sugar spike after spare ribs, small jacket potato and salad ( it was the small amount of BBQ sauce on the ribs)
Somethings can spike me one day and not another its trial and error.
Hope you get it under control without too many dietary adjustments.