Thanks for your query.
Diarrhea 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,khichdi,rice porridge.
like lactobaccilus sachet for 2 to 3 days.
Watch for features of dehydration
like decreased urination/increased thirst/lethargy/sunken eyes and in case you find any get him evaluated by pediatrician
Wishing your baby good health