Thank you for your query.
It is not unusual for children of this age to develop upper respiratory tract
infection in the way you have described. Most of the time you would not have to give him medication but once in a while he may require decongestants and even antibiotics. Observe him for the next day or two, give him steam inhalation and if there is no improvement then he may require medical supervision and medicines accordingly.
I hope I have answered your query to your satisfaction.
Wishing your son an early recovery.
Rajiv K Khandelwal