I have a tight pressure feeling across what feels like the top of my lungs, accompanied with mild discomfortable pain. However every now and then I get a crushing "showstopping" pressure in the center of my chest, followed by instability and light headed dizzy spells. I find myself gasping for air at that point. What could this be? I am 44, in good shape, and in the process of stopping smokeing for the past two weeks. This condition has been with me from July of 2013. I have had A full checkup by my g.p. and by the hospital. Im told it could be Arrthymia.