@sonofrio It seems you are dealing withan ID doc who is not familiar with thecurrent protocols for treating MAC.
This is not uncommon, as MAC is a rare infection and many docs rarely see it.
May I suggest that you find a pulmonologist who manages MAC and Bronchiectasis regularly as part of their practice?

In the meantime, here is a place where you can go to learn the basics of managing this infection:
https://connect.mayoclinic.org/discussion/resources-for-the-abcs-on-bronchiectasis-and-mac-ntm/
Basically, airway clearance is a method of intentionally clearing the mucus in your lungs, and can be accomplished many different ways. Here is a YouTube Video by Dr Pamela McShane, one of the experts in the field:

7%saline solution in a nebulizer, used before airway clearance, helps thin the mucus so you can cough it up more easily.

Do you currently see a pulmonologist?