@mbmax Let's answer this "...I want to switch drs and see what happens. Is this safe?" first.
When I was being treated for MAC and needed a pause in treatment, the very knowledgeable infectious disease dos told me "MAC is slow to grow and slow to go, so pausing treatment is not unsafe."

Since 2019, when I stopped antibiotic treatment while intermittent cultures were still positive, the philosophy around using antibiotics has changed a lot. Many more doctors advise "watch and wait", usually in combination with daily airway clearance, often including nebulized saline.

I did "convert" to negative for MAC about 6 months after stopping antibiotics, and have remained MAC-free ever since.

Has the new doctor suggested airway clearance?