I will keep my fingers crossed that a) your daughter won't be sick again tonight and that b) you won't get it!
Just wanted to add that we were always given Coca Cola or Rivella Red to drink as a child (cold but only a sip or a teaspoon at the time) if we had stomach problems because they have a lot of sugar in it and therefore even if we couldn't eat we got at least some "energy" trough the sugar. Furthermore it was a treat because this was not something we would usually have at home. We always liked that

If we could eat we got Zwieback (if we felt better even with a tiny bit of butter on it) or grated apples. I loved the grated apples because they were sweet but also "moist" and because they were grated you could eat it slowly again teaspoon by teaspoon. Hope that helps!