You may have a touch of emphysema. I don't know your age, but EVERYONE who lives past the age of 50 or so will develop a little emphysema, whether they ever smoked or not. Smoking accelerates this process. With emphysema what happens is the air sacs in the lungs loose some of their elasticity, so they don't expand or contract like they should. This means you can't breathe in as deeply as you once could and you also can't empty your lungs totally. With the limited air exchange you can experience shortness of breath, excess mucous and coughing and a feeling that you can't get a deep breath. Ask your doctor about a pulmonary function test, that will let the doctor know if it is emphysema or if perhaps you have asthma or some other problem.