Hi this is Kitt.........wow a tough one if your EKG and CXR are fine and your Pulmnary function tests were fine.
Any lab work done, an ABG, Complete WBC ?
Have you ever been dx with asthma? No URI or coughing. Your description of it being constant and worse with activity is concerning. I would suggest you talk with your physician about a stress EKG. Any chest pain?
Well I am not the professional but do not hesitate to call your physician if you notice any other alarming sx.
I will be following your posts.