I am having SOB symptoms and they have been ongoing for 8 months now. The condition came on suddenly. I had some stress at the time, but now I have very low stress for the past 8 months and not much improvement. At first I could feel my heart beating very strongly for 3-4 weeks. Then, those symptoms subsided and I have had shortness of breath ever since. I feel like I can fill my lungs fully, but that nothing happens when I do. I would describe it as an air hunger and not feeling satisfied with my breath (wanting more oxygen). When I try to yawn, I am not satisfied and I feel like I cannot complete my yawn. The feeling is always there when I think about it and intense physical exercise doesn't seem to make it worse, but my exercise tolerance seems to have decreased I can feel my heart pounding much more when doing intense anaerobic activity. I have had blood work, seen a cardiologist (fine EKG, ultrasound, exercise test), I do not have asthma (lung function test showed normal). Reading through this tread, I saw that this could be related to autonomic nervous system not being able to relax properly. Is there any way to test if your autonomic nervous system is working properly? What can cause this? Someone mentioned tick born diseases, I wonder if there is an underlying infection since it came about so suddenly. Or if something like blood clots/ pulmonary embolism can have caused this. Has anyone gotten a blood gas test? I wonder why this has not been recommended by my doctors yet to determine if oxygen and carbon dioxide are at the right levels. Would that test help to diagnose if oxygen or carbon dioxide was actually lacking, or if it is a more local issue, or just all in my head?