try this...
-350ml skim milk approx.
-5 pieces of ice
-1 scoop of vanilla protein
- some frozen strawberries, blueberries, etc...whatever you like, and don't be stingey
-half a banana
...blend till the ice is all ground up, but still a bit slushy.
...the ice make sit light on your stomach and easier to digest.
I used to always get an upset stomach as well, now i make a shake once or twice a day. I like my own protein shakes better than any shake stand I've been too.