Hello and welcome to the forum. Thank you for your question. I'm sure this is a stressful time for you. Has your doctor followed up yet to interpret the results? With regards to the nodule, size really does matter. Small nodules are more indicative of benign causes. Keep that in mind. This article is fairly detailed and long but does have information regarding how nodules are examined, what they look for to make a determination between benign or malignant. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5825309/ Please let us know what your doctor says and we'll go from there.
On PET/CT, the flip-flop fungus sign describes a situation when the draining lymph node(s) are hotter than the pulmonary nodule(s), usually a sign of benignity, such as granulomatous disease, mostly histoplasmosis, but not always. In terms of what to do next, that is a conversation you will need to have with your doctor. He/she may consider close interval follow-up imaging, or alternatively biopsy, depending on your clinical and/or laboratory scenario.