I am sorry you experienced such incompetence. It doesn't surprise me at all. I have stories I could tell you that are similar.
All you can do now is find a good pulmonary dr who is educated with MAC, it's a specialty. Most of them don't know anything about it. I've run into that also.
I see Dr. Colin Swenson in Atlanta, I believe he treats out of state people via telehealth. Where do you live.?
I went to National Jewish Health in denver first, but I live in Georgia so now see him.
If I can help in any way, feel free to message me. Bon