Hello, As you have written your symptoms and doctor is suspecting that you might be suffering from Asthma then you should complete you treatment regimen on short course basis . some more investigations should also be done along with chest X scan like total blood count, DLC, culture & sensitivity test of sputum, BACTEC test, lung function test. you should do oral gargle with salty luke warm water 2 times daily on regular basis, avoid very cold liquid drink intake and also protect yourself from smoke, dust, fumes which can aggravate your cough problem. Try to follow your doctor instructions. Take care bye.