Hi thanks for asking question.
Do you have done your chest x ray??? Do you have smoking history???
If you are smoking then bronchitis or emphysema like condition has to be ruled out.Chest x ray and pulmonary function test useful for it.
Sometime you can have allergic bronchitis like condition to particular substances.Blood may show
eosinophilia.Allergen test can be done.
If you are working in some high risk occupation like textile industry or coal mines then chances of asbestoses like condition ruled out.Chest x ray useful for it.
Examine your sputum if
weight loss present, to rule out
tuberculosis.Chest x ray also useful.
Rule out cardiac problems if suspected as cardiac failure or pulmonary
hypertension like condition can lead such problem.ECG or ECHO.useful for it.
Finally if x ray showing interstitial lung disease like suspicion then pulmonary function test done.Also rule out
atypical pneumonia by chlamydia or mycoplasma like organism by x ray and other investigations.
Osha root , peppermint oil , oregano are good herbal remedy.
I hope my suggestion will be helpful to you.
Take care