Thank you for your query.
The history provided by you suggests upper respiratory tract
infection which is most probably viral in origin. As it has not improved over time it needs to be investigated for any super added infection in which case an antibiotic may have to be started. The investigations will also reveal if it is infectious mononucleosis
I hope I have answered your query to your satisfaction.
Wishing your son an early recovery.
Rajiv K Khandelwal