If you still have NTM or MAC, it will show in a complete sputum culture no matter what antibiotic you are taking, but it may not show in an AFB (acid fast bacteria) slide sample (grown in 1-2 days) as is typically done in the local clinic or hospital lab. That is because mycobacteria are VERY slow growing, and the correct treatment takes time to select.

An AFB test missed my MAC and Pseudomonas completely. But a culture grown on on culture medium showed Pseudomonas after 7 days and MAC showed after 14 days. Then it took another 4 weeks to determine which antibiotics I needed to take for the MAC.

If they are doing a full culture at an experienced lab and showing no infection the possibilities are -
No infection
Not an adequate specimen (more saliva than sputum)
No sputum and a bronchoscopy is needed to get the sample.

If you are concerned about the spot on your lungs being active NTM, a bronchoscopy is the way to go, with the sample being cultured in a specialized lab and the results being reviewed by a pulmonologist or infectious disease specialist interpreting the results. This is beyond the scope of practice for most primary providers.

When you say you "can feel the spots again", how would you describe the sensation?

With Bronchiectasis, I often get a heavy, uncomfortable feeling. It generally means I have not been doing a good enough job of coughing up the mucus after nebbing, or I need to use my rescue inhaler to open up my lungs.

Have you ever tried increasing your airway clearance efforts when you get "that feeling?"

Sue