Protein molecules are huge and difficult for the stomach to break down....
when I was in days 1-4 of recovery
I tried sipping protein shakes, and OMG, it was a horror show.
Bananas are good, and they have potassium. Piping hot chicken broth, pasta, maybe some dry toast or an English muffin. Baby your stomach. I had a heating pad on mine 24/7 for the first 16 days.