I've been PMing some people, but I wanted to post the different opinions from the neuros on here for everyone.
The professor neuro saw me. And I also saw my normal neurologist last week as well.
All 3 neuros, and the neurosurgeon agree that the herniations in my cervical neck are not the cause of what is going on in my shoulder/deltoid/arm. The herniations at c5/c6 and c6/c7 are too low to affect my deltoid and shoulders. All diagrams I see online show that the deltoid is c5/c6 level, so I don't get it, but I will accept their opinions.
The professor neuro and my normal neurologist told me that the neuro that diagnosed me with Plexus Neuritis
is wrong.
Normal neuro said: In plexus neuritis, I would have a limp arm and definite atrophy, which I don't have (something my husband and I wondered about too, we don't see any atrophy and thought the neuro could see something we don't). He took blood for lyme disease (results this week). When I asked him if it is not plexus neuritus, and not related to my herniations, then what is going on? He literally said, "I don't know either." I asked him what he thinks about my abnormal EMG and he said:
"Anyone could have those results."

He did not look at me, did not examine me, nothing.
He said the neuro should have never put me on cortisone. After this lyme test result comes back, I am never going to him again.
Professor neuro: Did a clinical neuro exam (no EMGs or anything), strength is still there. He said the same thing about plexus neuritis and could see that I have no atrophy in my shoulder. He said in 30 years, he's seen maybe 5 cases of this, and I don't have it. He said the EMG of the other neuro showed findings, but it could very well be that something attacked me, but that I have my strength back, that I am getting better.
He said the cortisone was a good idea. To keep taking gabapentine, taper off the cortisone as planned and continue physio.
Both the professor neuro and the normal neuro, and now my primary care doctor, think it could be something attacking me or something auto-immune. My primary care doctor is going to re-order the blood tests after the cortisone is out of my system. I will start acupunture with her for my shoulder/arm (since the pain is still very high) and she will also give me an infusion of stuff to help nerves heal.
Meanwhile - going back to twitching - healing or dying:
The arm L. twitching - hot spots - have died down a little. I have felt my heart beat in my arm lots of times, pretty intense. Although it still feel "off" as far as strength and coordination goes, I feel it feels less "off" every day. So perhaps this twitching is positive and indicates healing.