I know at the moment where I live gastro bugs are practically an epedimic, I spent 3days in hosp with my 4mo & while in Casualty they had 10 cases of gastro in toddlers, I'm sure after your stay you were given some info, but DON'T worry about the food, at her age milk is more than sufficient. Infact cut out all solids so you can rule out food allergy
With the fluids offer small amounts often. I was chatting to one of the nurses while we waited for ds test & she said they say 5mls every 5mins for vomitting under 1yo. & 10mls every 10, when they are bit older.
For diahrroa, I would offer her "her daily milk intake spread over 3-4 times as many opportunities as normal 9if she normally has 4 bottles a day offer her 12-16 very small ones & offer cool boiled water in between times... offer her something to drink every 15mins she is awake to aviod her dehydrating. Keep a log & make sure it is fairly close to her normal intake.
My ds#1 got sick (although not stomach bug) at 9mo & didn't eat solids for 3 weeks, He still took bf & my Dr & Early childhood nurse were very happy with that. He made up for the weight gains later & ate like there was no tomorrow. He got sick 10days ago & didn't eat for a week, these last days he eats everything not locked down... babies & toddlers are great regulators when given a chance, so just worry about the fluids