So glad you paid a visit to this sweet little forum!

I am so very sorry about the RSD battle. The loss of function to your hand sounds very frustrating!
My first (encouraging) thought that comes to mind is that it's a good indication that you may benefit from the SCS, especially since the TENS unit seems to do you good. This could be a good indication that your hand is willing to 'respond' to the type of treatment the SCS would offer. The pain signals would be blocked by the stimulation.
Have you lost much muscle tone to this hand? (Atrophy)
Hopefully the blocked pain signals would allow you to get better PT and strength back.
There are several here who have the cervical stimulators. Hopefully they will pipe in. It would be good to know if you will regain motor function to your hand.
Like Mark, I too have a lumbar SCS for lower extremity nerve pain, which truly does a wonderful job of covering over the burning pain. Initially, I responded (very briefly) to SNB injections, but that was encouraging enough to go thru with the trial since I DID respond.

I do not know if the stimulator would help you to regain function or not. All I do know is that it does a wonderful job of covering over burning nerve pain.
I recall briefly taking Mobic for a wrist injury. I believe it is an anti-inflammatory?
Also, it might be good to address your Dr regarding the new 'shooting' pains you are experiencing. I've heard things regarding the nerves possibly trying to reguvinate and shooting pains could be part of this, but, this may be hearsay. May be a good question to bring up.
I'd certainly express your concerns about the possibility of the RSD spreading. SCS's have been known to carry a risk of spreading.

I wish you the best! Please keep us posted on how this unfolds for you.

Caring,
Rae