Hi, I posted a while ago about my Brachial Pruritus. That manifest for me with arm itching that originates in the cervical spine. See here: https://connect.mayoclinic.org/discussion/this-stretch-helped-relieve-my-brachioradial-pruritus/

My wife suffers from chronic shoulder and arm pain that apparently has a similar origin (cervical spine nerves contacting surrounding tissue).
When she does the stretching that I use for relief from arm itching she gets pain relief as well. She still takes her pain meds but uses the stretching for relief on bad days. And I think, possibly has fewer “bad days” by stretching daily as a proactive measure.
I just thought I’d share this with you as a possible help.
I’m no medical professional, but just another patient in the struggle, hoping my discovery might help some others in their struggle.
Don