What Causes Chronic Cough Along With Shortness Of Breath?

i AM A 68 YEAR OLD CACAUSIAN MALE, REASONABLE HEALTH, 212 #, 6 EVEN. I HAVE A HISTORY OF ALLERGY REACTIONS TO POLLIN, CHOCOLATE AND INSECT STINGS. WHILE IN HIGH SCHOOL, I DID HAVE MONO FROM WHICH I RECOVERED. ABOUT A MONTH AGO I BEGAN HAVING SESSIONS OF VERY HEAVY COUGHING, FREQUENTLY CHAIN COUGHING TO THE POINT THAT I WOULD RUN OUT OF AIR. ON TWO OCCASIONS RECENTLY, THIS LACK OF ABILITY TO BREATH IN HAS FOUND MY ON THE FLOOR WITH MY HEAD BETWEEN MY KNEES.I THINK I MAY HAVE PASSED OUT.) I HAVE BEEN TAKING DOSES OF ROBETUSEIN RED AND YELLOW DEPENDING ON THE TIME OF DAY, OTC ALLERY PILLS IN THE EVENING BEFORE BED. THESE TREATMENTS DO NOT WORK ALL THE TIME. PRECEEDING MOST EVERY COUGHING SESSION, I AM AWARE OF A MILD DRIPPY HEAD . BLOWING MY NOSE PRODUCES CLEAR MUCUS. THE COUGH IS NON-PRODUCTIVE. ASIDE FROM THE USUAL ACHES AND PAINS OF BEING 68, I AM NOT AWARE OF OTHER OVERT RELATED SYMPTOMS. ANY IDEAS?