@ Jesse Shields, a couple of thoughts:
First and foremost stick with Dr's advice.
Common first steps are to avoid all loaded overhead work, dips and other shrugging movements. If recommended use some form of cervical traction/decompression to see what sort of relief if any it gets you. This did nothing for me, but some folks get a lot of relief.
NSAIDs are useless for the most part, don't bother.
The pain in your lower back is probably unrelated to the cervical issues, and some of your other symptoms might be unrelated as well.
Is there significant shrinkage of the muscle compared to the non-symptomatic side?
Whatever conclusion your Dr comes to once you get the MRI, if possible get a second opinion from a neurologist, even if your current doc is also a neurologist.
Explore the possibility your posture is part of the problem and if so address it. Almost certainly there are positive changes you can make if you can ID questionable posture habits. This includes how you sleep.
Rotational stretching helped me the most, consult w/ your Dr or PT to see this if this is contraindicated in your case. Loosening up the muscles around the neck and traps can make a big difference over time.
Whatever exercises you are cleared to do, get right on it. There is not a ton of research on this but exercise does appear to help restore function in partially impinged nerves. In my case I bumped it up a bit and followed more of a BB protocol with a lot of training to failure using submax loads, something I hadn't done for quite a few years prior.
Nobody can say what your final level of function might be restored to, assume it will be nearly 100% and train optimistically. I went from being in excruciating pain to 90+% restored, although I'm sure I could jack myself up very quickly if I stopped applying all the little correctives I've learned.
Listen to what your body is telling you - when my symptoms subsided enough to get back to training I still had to avoid some postures without taking additional steps - bent rows, pushups, other lifts where my head was tipped over unsupported I had to keep my chin up. Working a lot of overhead pressing back in led to more pain and stalled progress and had to be discontinued.
Be aware that some localized muscle pain that feels just like DOMS but persists for days or shows up unexpectedly could easily be from the impinged nerve. Again, posture and exercise selection are very important pieces of the puzzle. Be careful reintroducing exercises and keep tabs on how they are tolerated.
Really nice video that doesn't address specific exercises but gives a great run-down on the condition:
Personal thank you North Coast Miller for introducing me to Dr. Mandell. Stuck out here in the Philippines with a new C7 injury and his videos have really helped me to not only self-diagnose my injury but also helped me lay out a recovery plan that I feel confident with. Thank you!