Not diagnosed with MAC but I have CRS (chronic sinusitis w/o polyps). If I have a sinus infection it usually starts with some trigger, which leads to sneezing and some crusting at my nose. If left untreated by my home program it usually ends up in my lungs and they get gunkier even though my sputum sample does not grow anything. The respiratory culture usually show lots of neutrophils, however, indicating inflammation and possible infection (probably colonization in my case). I do not necessarily cough more during a sinus infection unless it has gone to my lungs. Even without infection my "cough times" happen several times a day anyway (at night, eating, talking a lot, laughing etc).

ENT told me recently that for sinus infection to clear it needs 14 days of antibiotics. Sometimes more if it's recalcitrant. It's difficult to get a nasal culture unless the infection is very active. My home program includes rinsing with saline and budesonide, steaming (when there's pressure/stuffiness), Sudafed, Tylenol. For the crusting I use Ayr and sometimes muprirocin sparingly. All this on top of airway clearance 2x day! Hope you feel better!