Countinue cough in a child age 6

Hi There,

I am bit of offmood here as I can see my son coughing a lot while doctors treat it normal so no medication.

I am in UK since last 4 years only, asian (Indian) origin, my son was born in India only. The problem is, when is summmer time and not much cold, he is alright. As soon as its November and temp is down he coughs a lot mostly dry. In the morning he coughs a lot with some phlegm.

The cough sometimes aggravate when he plays. I could hear some chesty sound sometimes and sometime blocked nose with and without phlegm. So its not dry cough either.... Not sure what it is.

He is happy child, takes less water (though we force him to drink a lot - the luke warm), found of juices, hyper active, no anger, very cary about his younger brother. Eating is good. No other issue.

I tried Chamomilla 30C, Nux Vom 30, Belladona 30, Bryonia 30 ... but no gain.

Please help