dry non productive cough for yrs... pulmonary fibrosis

I have had a dry non productive cough for about two years. It is also accompanied by other symptoms such as shallow breathing ( I feel as though I'm not getting enough air ) , pain when I try to take a deep breath, dizziness, lightheadedness, and fatigue. Its also hard to breathe when i lie down. I used to be very active but now everything seems to strenuous for my energy and airways. I've been tested for asthma, GERD, post nasal drip, and have been medicated for all of the above including allergies and anxiety. All of the tests came back negative and none of the medications worked. I'm wondering if something more serious could be going on. I'm only 20 years old but pulmonary fibrosis has seemed to be the only disease that matches my symptoms. I was wondering of that could be a possibility?