For his teething
pain, you may give him teethers/ gels to be applied on the gums/ Acetaminophen
in a dose of 15mg/kg/dose given twice or thrice a day if he is very cranky.
Have you got his chest examined too?
He might need cough
If chest is clear and cough is too distressing, you may ask your doctor for cough suppressants.
If he has a blocked nose, it might too disturb his sleep. You may give him Nasoclear drops 2drops in each nostril
four times a day.
Do not use over the counter cough preparations. Discuss with your doctor who has examined him.
Hope my answer helps you.
Wish your son a speedy recovery.