Thanks for your query.
Your child is having acute gastroenteritis
which is usually viral in nature and takes few days to settle.
Most important is to maintain hydration.
Give oral rehydration solution sip by sip after each loose stool.give coconut water,lemonade,curd,boiled potato,banana.rice porridge.
In case of persistent vomiting antiemetic like domperidone is to be given in prescribed doses.
for 2 to 3 days.
Watch for features of dehydration
like lethargy/decreased urine output/refusal of feeds and in case you find any get him evaluated by pediatrician
for further management.
Wishing your child good health.