My goodness...4 miles on the treadmill 5X a week is phenomenal!! I am no Dr. but strongly suggest you seek a second opinion, preferably with someone that specializes in bronchiectasis. Often bronchiectasis goes hand in hand with other "bugs" such as MAC so I think that someone that specializes in your disease would be beneficial. By the way...there are many on this site that would love to do one mile on a treadmill without being winded. Please do not take the word of one person for a diagnosis....especially when it seems to be so negative. My Dr says he believes I have had Bronchiectasis since childhood.... A good diagnosis is imperative along with knowledgeable maintenance. Are you near any Mayo Clinics or perhaps National Jewish Health in CO? I know lung disease diagnosis is frightening but try to relax till you get good professional advice. I discounted the advice from my local pulmonologist and headed to Mayo. It was there that I got good explanations, help with managing the diseases, and felt reassured with the Dr.'s recommendations. I am mild with both MAC and Bronchiectasis and believe I can remain that way. Many times you just need to adjust to the new you. At first, I was overwhelmed by a diagnosis, but feel fortunate to have the diagnosis so that now I can take good maintenance measures. Good luck and know that everyone on this site is here to help guide you.
Kate