Thank you for your query.
I think it is viral fever
Some viral fevers may extend to 10 days.
You may go for a blood test
to confirm it.
Give him lots of fluids and give him paracetamol
Consult your doctor if the problem persists.
If you have any further queries you are free to consult me.
Hope this answers your query.
Wishing a speedy recovery.
Have a nice day.