Now that she's on antibiotics, she will probably feel better really soon.
Umm, my gut reaction says, avoid food that are major allergens (soy, dairy, gluten, etc) while she's on antibiotic and also afterwards until she reestablishes her gut flora. I don't know for like couple weeks, I guess.
what kind of probiotics are you using?
Seroyal/Genestra brand is highly recommended, because it has really high bacteria (the goodies) count, which delievers more bacterias even after some of the die off in the stomach. You can buy it here.http://www.costlessvitamin.com/catal...oducts_id=1491
Maybe little bit of vitamin C, child dose.
After her gut flora seems established, you can give her lots of fermented food, too. Like, sauerkraut, homemade kefir, raw kombucha etc.
Hope she's feeling better already.
and remember, antibiotics can be harmful when not used correctly, but it saved lots of lives!