Since all of you had same problem, it might be a virus affecting the respiratory tract
Is it a dry cough
or he has phlegm when he coughs?
What do you mean by choking
when exhaling out? Do you hear any sound at the end of cough? A whoop is a deep inspiration that occurs after a bout of cough. During cough, air in the lungs are expelled out and when it is severe, the child takes in a deep inspiration to take in air that we hear as whoop. It can happen in pertussis
and some other viral infections too(Pertussoid cough).
Cough more at nights can be due to Asthma/ reflux/ post nasal drip
infections/ just an irritating throat. This throat irritation
is more common when the season changes, when you switch on heater with out humidifier etc.
If its the throat that causes the irritating cough, cough medicines that contain soothening agents like menthol will be of use along with adequate water and humidification. Cough suppressants can be used in such cases.
What I suggest is to have a word with your doctor, find out the cause of the cough and then take the appropriate treatment.
Hope you find my answer useful.