She is suffering from Acute gastro enteritis
means infection in stomach and intestine.mostly due to eating some food which she is not able to digest.In such a case you only need to take care of her hydration status ,otherwise everything is normal.
You can give her Ars alb 30 2 tabs before giving her any food and continue this for 2 days.she will recover in this much time.You should take care of her diet.Only give her liquid diet
and fruit juices prepared at home.
Check for her urine frequency ,if she is passing urine regularly then her hydration status is ok.
Hope this helps,