IS IT PULMONARY OR CARDIOVASCULAR?

SHORTNESS OF BREATH, FATIGUE AND VERTIGO AFTER SHORT INITIATION OF WALKING.  
HACKING COUGH EVENTIALLY PRODUCES MUCOUS WHICH IS CLEAR IN COLOR.
MUCOUS APPEARS IN THROAT OVER TIME IRRESPECTIVE OF COUGH.

[National Jewish Health]

What you describe, with somewhat limited information, could be due to either the heart or the lungs.  Examination of your heart and lungs especially if you have a history of either heart or lung disease, examination of the mucous since it can be clear with either condition, and a chest x-ray should enable your doctor to answer your question and prescribe the appropriate therapy.