What Causes Strange Sensations In The Chest Despite A Normal ECG Report?

For the last year and a half I have had this strange sensation in my chest. At first, since I work outside in the woods, I though I had pollen stuck in my lungs. My chest feels heavy and it feels like when I breathe the air goes into my lungs, but if feels weird like it is traveling through smoke or some other obstacle. It is hard to describe. I have no shortness of breathe. I seem to breathe fine. Also some times, not too often, by heart feels like it skips a beat or beats to fast. I have been to a cardiologist and had a stress test, Ekg, Echocardoigram and they all came back ok. I have been to a doctor to check out my lungs. Had a chest CT twice and a neck Ct. All was ok. Also was tested for asthma, which came back negative. All three doctors are telling me I am ok, but I do not feel ok. I constantly feel the chest discomfort. Any suggestions