@ameliar I've had a cough when I wake up in the morning for at least a year, maybe much longer, with minor coughing once in a while during the day. Like you, I thought that the cough was from post nasal drip. However, in late August a year ago, I coughed up some blood while lap swimming. I went to the ER and was “diagnosed” with walking pneumonia. A CT scan revealed some tree-in-bud in the middle lobe and a few nodules. I was put on levaquin, but within 3 days, my left extremities became numb and tingly so I was switched to Zithromax for a week. It didn’t seem to do anything, because the minor cough persisted. I saw a pulmonologist because the CT scan called the nodules “spiculated,” which typically means cancerous. The pulmonologist practically laughed me out of the office, saying it wasn’t cancer and I was perfectly healthy. Six months later, I had another CT scan because of the nodules. It showed similar results ("redemonstrated focal bronchiectatic changes" but little change in nodule size). The pulmonologist then suggested I do a sputum test. I cough very little, if any, sputum, but was able to get a very small sample last month that tested positive for MAC.
I am otherwise a healthy 70-yr-old, who walks a few miles almost daily and loves working outside on our 2 acres. Until my diagnosis, I was swimming laps 2x/week, which, ironically, I was doing to help my lungs. (About 35 years ago, I worked in a government chemistry lab and had routine health checks, including a lung test that suggested I had low lung capacity. However, at the pulmonogist’s last year, I had a pulmonary function test that came out 100% lung capacity for my age.) After reading about MAC, I've stopped lap swimming and gone back to jogging on my prior swim days. (I used to jog routinely.) I have an appointment with an infectious disease doctor at the U of Michigan Hospital for next month. I’m very sensitive to antibiotics from my sinus infections and have no interest in taking them unless I get very sick without them, so I plan on just continuing to exercise for the present and have a CT scan annually, or as recommended by the doctor.