You have recently suffered a chest infection
that is for 1 month, and now there is no cough.
If sputum is still persisting if there is no reason as X ray
chet is normal it will subside in few days time .
But if there is a reason like smoking
is there then it may be sign of bronchitis
if irritants like continues it may become chronic Bronchitis so avoid any smoking and even any kind of smoke and air pollution and even any kind of chemical fumes.
If you will take care you will improve.
I wish you speedy recovery.