I am going through a similar thing, but I don't smoke. Out of nowhere, I suddenly developed asthma 5 weeks ago. All tests come back normal. Normal chest xray and CAT scan of the lungs. I am beginning to think that mine is being caused by candida or is a hormonal issue. Not that it's not obvious, but the first thing you should do is stop smoking everything, legal or otherwise. My uncle died of emphesema and trust me, it's not the way you want to go. He was a smoker.