Scared by new Lund nodule

1. Hi. This is my first time posting here although I have read and been comforted by lots that I have read so hoping to have my new worry put in perspective!!!
2. I was diagnosed with TNBC in Dec 2018. Treatment...surgery, chemo and radio finished May 2019. Whilst getting my pre radiotherapy x-ray do ehing was spotted on my right lung so I was sent for a CT scan with contrast. Result of that was no Mets but an area at base of right lung showing patchy and active changes....whatever that meant.....however oncologist was not concerned.
3. Now, a year and a half later I went to GP as having some back/ lung pain especially when lying down. I was sent for a chest x-ray on Tuesday and GP called me today saying a small nodule is showing on base of my left lung and a CT scan needed to get a better look
4. What really concerns me is that this is new and obviously not seen on last CT
5. Has anyone had this experience and what was your outcome? I am really quite worried that a new nodule indicates metastasis

Thanks. Any experience you can share would be much appreciated