Welcome to HCm,
From his symptoms it seems that due to congestion in nasal mucosa, nose is blocked.
This condition gives problem at night only as at this time nose is totally blocked giving air passage blockage.
Give your son decongestant syrup like Benadryl
, cyneral, D-cold
You can put Otrivin
pediatric nasal drops in the nose during night time.
Ok and bye.