Thanks for your query.
Your child is having respiratory infection with fever
which is there for 3 days.,which in most cases is viral in nature and settles in few days.
I suggest you to get him examined by pediatrician
for proper management.
In the meantime give paracetamol
for temperature management every 6 to 8 hourly.
as per dosage for 2 to 3 days.
Give plenty of fluids,warm fluid will be soothing, give vegetable soup,fruit juices.
Wishing your baby good health.