Let me preface this - I am not a doctor, but a lung patient who had a "mystery illness" for over 4 years before it was properly diagnosed. My symptoms were coughing, fatigue, shortness of breath, increased asthma symptoms, and coughing up dark green sputum. I was treated for bronchitis, pneumonia, intractable asthma - over and over, with short periods of relief. I was seen by my primary, as well as by Urgent Care and ER docs while traveling.

In 2018 I could no longer walk one block without pausing, and was coughing 24/7. My PCP was on leave, so I was seen by her sub, who ordered a new lung x-ray & thought she saw "something suspicious" so she referred me for a CT scan.

The radiologist reported many abnormalities in my lungs & I was seen by a pulmonologist who diagnosed bronchiectasis & suspected 2 likely lung infections. He suspected Valley Fever but the test was negative. Then he sent in 3 sputum samples that were cultured & after one week I was diagnosed with pseudomonas & treated. Several weeks later they also diagnosed MAC (Mycobacterium Avium Complex) a very slow growing relative of TB. Routine blood tests do not show these infections - they hide deep in the lungs.

Pseudomonas is almost always treated with specific antibiotics after identified. MAC may or may not be treated, depending on symptoms and severity.

As long as you are feeling better and you are going to be watched closely, "wait and watch" is a legitimate strategy. But, if you begin to feel ill again, or the mass grows, and you again test negative for Valley Fever, you might want to explore the possibility that you have one of the more uncommon infections, especially if you have ever had lung problems before.

Have you had lung issues in the past, or are you a current or former smoker? Do you have other risk factors for lung cancer like family history or exposure to a toxic work environment?
If so, you might want more aggressive research. Otherwise, if you are comfortable with the plan, go for it.
Sue