You might want to see if it's Thoracic outlet syndrome, which is entrapment of the nerves as they pass from spinal cord through the shoulder into the arm. I experienced numbness (and loss of blood flow to two fingers) simply because my seating posture was incorrect - my keyboard and arms were too elevated. It can be mistaken for carpal, so do check into it.

Great podcast, thanks. Hope you feel better and get an answer soon. FWIW, I've found the evergreen advice "trust, buy verify" to also be accurate when dealing with doctors and specialists.