chronic tingling/burning in middle/upper back

I have been struggling to find an answer to my chronic back issue for almost 7 years.  I am a 35 year old, healthy and active woman (former dancer and gymnast) and sometime in the year after I had my first child, I began experiencing a very intense, localized tingling in my left, middle back (about one half inch to the left of T12, very deep beneath the paraspinal muscle).  It felt like someone was shooting a laser beam into one tiny spot in my back.  This burning and tingling has increased dramatically over the past year, and now encompasses that same mid-back area straight up to my upper back (also left side, just below my neck, inside my shoulder blade).  It is constant and the tingling feels similar to being connected to electrical stimulation.  I had a cervical and thoracic MRI two weeks ago, and the results were negative - no bulging discs, no spinal stenosis, etc... just "mild degenerative disease in the middorsal region."  I have tried chiropractic care, massage and physical therapy all to no avail.  The physiatrist who ordered the MRI seems to have no idea how to proceed.  This feels very much nerve-related, and yet I have no idea what is causing it or how to treat it.  I did not experience any particular injury, and the tingling is at its worst when I am doing everyday tasks like laundry, dishes, cooking, brushing teeth etc... anything in which my focus is slightly down.  Any thoughts or help would be greatly appreciated.