Do you happen to have Powerade, Gatorade or Pedialyte packets on hand? That could be a big part of the weakness, it doesn't take long to dehydrate and throw all the electrolytes into imbalance snd these work within a day, might feel better by tomorrow evening. i
Potatoes are good as you heal, they don't scratch or scrape any of the swollen insides. I will sometimes add a bit of plain ground chicken or ground beef for protein, you'd be surprised how long a person can live on potatoes with a touch of protein (grocery store roast chicken works too if you aren't up to cooking)