Assuming your diagnostic workup is benign, consider sending to PT to mobilize the spine and stretch the paraspinals. Have an Osteopath or Chiropractor manipulate/adjust the T-spine a couple times to see if it helps. If not, then move on to more invasive, costly, and dangerous procedures!
EDIT: sorry mehul, I just remembered you are a physiatrist so you probably already tried the above.
If the thoracic MBB are of no use, could consider thoracic discogram as a diagnostic tool. If you don't want to do that (considering the very difficult anatomy at those levels), could try paravertebral blocks in the hope that in the process of blocking the gray rami and sinuvertebral nerves you might get some lasting relief if you are lucky.