What are the chances that the 5mm nodule found in my CT scan is cancerous?

It was found two days ago after I had gone to the ER for chest pain/minor trouble breathing by coincidence and not believed to be the cause of either symptom. They want to give me another CT scan in 6 months. About a year ago, a doctor had told me I had "thickening in one of my lobes" but that it was so minor that it was considered to be nothing.

Should I be concerned? Are both things (thickening in lobe and nodule) connected? I'm kind of anxious about it, and would highly appreciate some expert opinion.

Thank you for your time.