Your symptoms are suggestive of Bronchial Asthama.
Chennai is highly polluted place so this must be very common there.
You need regular and long time treatment from a qualified doctor.
He shall suggest some medication for immediate relief and then long term medication. This is not some
flu which will go away with a few days of treatment. You will have to be persistent with treatment so also preferably doctor.
In the mean time you shall start breathing exercises to increase lung capacity.
Plain steam inhalation (with very warm water and not boiling water). If
cold things are causing aggravation of the situation, then better avoid it.
Are you doing any routine exercises? like walking, running, swimming, cycling etc.
If not then start walking at easy pace. Start with five minutes, as I presume you are not habitual to the exercises for your condition. Start at slow pace. Increase by two minutes every second day. increase pace every seventh day and maintain.
Make habit of exercise like having food every day.
This with proper medication shall help you.