Thanks for your query.
Your son was having fever with gastroenteritis
which is mostly viral in nature and takes few days to settle.
This is good that fever has settled.
For vomiting you can give antiemetic like domperidone
as per dosage.
Most important is to maintain proper hydration.
Give oral rehydration solution sip by sip after each loose stools.give coconut water,lemonade.curd.banana.boiled potato.rice porridge.
Observe for features of dehydration
like lethargy,decreased urine output,increased thirst,sunken eyes and if you find any get him evaluated by pediatrician
Wishing your baby good health.