Back pain when I breathe in, is this TMS?

Sure, why not? Mind you, I can't diagnose TMS based on a two-line post - especially considering I'm an accountant, not a medical professional - therefore our permanent disclaimer says that you should be medically checked out if a new symptom concerns you.

That being said, based on my lay person's understanding of physiology vs. neurology, I certainly can assure you that our brains are capable of creating any physical sensation whatsoever - because all physical sensations are actually generated in our brains. Phantom limb pain is proof of this - and it is widely accepted as purely brain-based by the traditional medical community.

People are anxious to find corroboration that their particular symptom has been experienced by others, who can somehow prove or assure them that the symptom was TMS. The problem with that need is that we've seen countless cases of people with crazy one-of-a-kind symptoms - which disappear when they finally make a commitment to doing the emotional work.

Over the years, it's become clear to me that our brains are perfectly capable of creating a unique symptom precisely because the person will be unable to find anyone else who has ever experienced it - thus effectively remaining mired in fear.

It's the perfect trap in many ways - but you don't need to fall for it.