A nodule is due to infection, inflammation, or tumors. A nodule that is 2 centimeter (20 millimeters) in size or smaller is very unlikely to be cancer. As a 36-year-old non-smoker, with a CT scan that shows nothing other than the 6 mm nodule, the advice to repeat the CT scan in 3 months is sound. That is what I would do, if it were my x-ray. The odds are very high that this is nothing to worry about. Only if the nodule has grown would more testing be done to know what the nodule could be.
I just want to clarify that I have no symptoms. I had to undergo an x-ray for a work visa to a different country. That's when all this happended.