For me it is a deep kind of ache...lasts only a few seconds then goes, but it foesnt seem muscular at all, or on the muscular level. It sometimes even occurs through to my chest. Was yours "deeper" than the muscles as well? I have also had a host of odd symptoms that have come and gone over the past few months and have been under quite high stress.
I would say it felt pretty deep in there, yes.. But more like a stinging pain, it was pretty intense at it's worst, but with me, the pain often changes in severity amd location, though for the past few months, it's setttled into my back... Either my Thoracic or Lumbar region. At least, I don't have Sciatica at the moment, though I also have history in that arena too... If you've ever read Dr. Sarno's books, there are a wide variety of maladies associated with Mindbody Syndrome or TMS and though he says the condition is caused by repressed emotion from our past, primarily rage, I personally think current stressors, especially if the stress is unusually high or long term can also perpetuate symptoms...
I can certainly understand your concern with it affecting your chest area. If you're especially worried, you can always check in with your primary care Dr, though if you're like me, I wound up going to multiple doctors, ERs, urgent care clinics, and physical therapy, had an MRI, xrays, even saw an Orthopedic specialist, and like most people on here, had the sh** scared out of me with all the traditional diagnoses. (herniated disc, degenerative disc disease, scoliosis.. Blah, blah, blah..)
However, most of these conditions are described by Sarno as rarely the culprit in the causation of pain, merely "gray hair of the spine" that comes with the natural aging process..
Aghhh, growing older is not for the faint of heart!! If I had to venture a guess though you're symptoms DO sound very much like TMS. I'm fairly new to the site, only been about a month, but it's really great to connect with such kind, empathetic people who really GET what you're going through. I find myself often feeling a little isolated because many people do not accept that TMS is a real thing, so having this forum is a Godsend... Hope you feel better soon!