There is congestion in chest.
This is the main reason for coughing.... And to treat cough means to relieve congestion.... He might be having wheezing while breathing or suffocation after lying on bed, which affects sleep.
May be he will get little fever.
Next Steps
You have to consult me directly if you want homoeopathic treatment for your little one.
Antibiotics will treat the cough but for Small kids homoeopathy is mostly preferred since its harmless.