My 4,5 year old boy have a wet cough (initially was dry) for 3 weeks especially when sleeping. had much phlegm,dont spit, but swallow. no other symptoms, is well, happy, energic boy. when is playing the cough is rare, 1 per hour. is normal?

Not normal: So sorry your sweet boy is I’ll. Three weeks of nighttime coughing is not normal. It is still possible this is in the realm of a resolving viral infection if his cough is improving day by day. If the night time cough is stable, he may have a sinus infection needing treatment. We may be able to help you with a prime visit! Otherwise get him to your local pediatrician. Best of luck!