As u might have realized,u need to increase ur lung's ability for permanent cure.
First do kapalbhati, pranayama on regular basis.
To avoid production of excess mucus and to expel it out take vasakarishtam 2tsf thrice daily.
Pipali rasayana course to be taken under ayurvedic doctor.
Of course u have to avoid stress
and allergens like chemicals,dust etc.
Wish u good health.