I have the same problem as you have now

I did everything to figure out what it is but in vain. doctors gave me CT MIR endoscopy heart and lung function test. found nothing. then they said it is functioal thing. I believe there is a inflamation locus in the soft tissue close to your bronchial. but it is not on the wall of it because the bronchial is very sensitive to anything. now the only solution i can try is "ba huo guan" it is effective for me.