Yeah you might be right. Your kid seems to have an episode of gastroenteritis- which is mostly viral.
She will get okay in a couple of days. You need to be sure she drinks well and she passes urine atleast 4 to 5 times in a day.
You may give her plain water, soyamilk, vegetable soups, plenty of curd, porridge made of rice, sago etc, boiled potato, banana etc. Curd will be of real use as it contains lot of pro-biotics naturally.
Do not force feed her. Offer these food and fluids in small amounts frequently.
If she continues to have vomiting
on and off, you may give her medications like Ondensetron in right dosage.
However if she is very cranky and irritable, she has high grade fever
, you see blood in stools, frequency of urination is less- you need to see your Pediatrician
Hope my answer helps you.
Wish your daughter a speedy recovery.