I have te same thing esp in morning. Mostly yellow after 5 weeks being on ethambutol and azithromycin.
I was dx with MAC 5 years ago and was stable until last may when i developed metahumanpneumonia virus, was hospitalized and on isolation for 8 days. I was very ill.
This past april developed RUL pneumonia, on 10 days of Ceftan but still had congestion. I was then hospitalized for 5 days IV Zosyn, d/c home on 5 days Ceftan. By the 6th day had frequent bms which lasted 8 days. When I recovered, started MAC tx because there was no change in chest xray and ID consult said I did not need Zosyn! MAC needed to be treated.