[At first it started with me sleeping on my hand under my pillow and waking up with complete numbness from ring and pink up to my elbow. I was diagnosed with Cubital Tunnel Syndrome. Some odd things started happening though - the pain was excruciating and then my left arm started to mimic the problem in my right arm and hand and so I was diagnosed with Reflex Sympathetic Dystrophy Syndrome]
and
[P.S. The numbness, claw fingers, pins and needles, numbness, weakness, cold skin and paresthesia has cleared up in my right hand (the Cubital Tunnel issue), and I can finally hand write again for the first time in six months!!]

You might want to visit our thoracic outlet syndrome forum (TOS ) for short..

useful sticky threads for TOS- good place to start post #1 has tons of info links.
http://neurotalk.psychcentral.com/thread84.html

What you describe above is often some of the symptoms for TOS, also the cubital tunnel - could be a "double crush" or the actual cause is coming from the TOS area- roughly the neck/shoulder junction.
The nerves and blood flow for arms go thru the small space and if it gets pinched can cause all sorts of pain and issues.
Also the holding arms up to wash hair problem.. another TOS sx..

[ shooting pain from my neck down my shoulder - just had an MRI on Saturday..]

Can you get a copy of the MRI written report?
Share it if you like, we might be able to help understand it.