id recomend small amounts of diluted apple juice, say 10-20 ml every 30 min.
small sips are better than big gulps.
also let her suck on ice cubes or blocks if you have any.
if you notice high temp or signs of dehydration like no wet nappy in 12 hours, take her to the docs.

my DD gets this regularly well every 2-3 months she just has a sensitive tummy and picks up all the bugs that is what we get told to do every time

and its what i tell m y patients to do.

if you can get hold of some hydrolyte it is great..