I'm not too familiar with yoga but I don't think it should be much of a problem. Stretching will also help. Listen, there is every reason for you to have hope because you have a condition that has a good prognosis. You will recover.
I don't think your conditions are related to each other. You just got dealt a bad hand. People with Parsonage-Turner typically make nice recoveries (some quicker than others). The important thing (and this might be a bit too late to tell you) is to rest and not lift weights at all while you're recovering. Doing so will prolong your recovery. I stayed out of the gym for nearly a year. It was incredibly difficult but it allowed the nerves to recover properly.
Yes, I had the pain you are talking about and it absolutely sucked. I never took any meds or had any type of therapy. There really isn't anything that can be done, unfortunately. You should still go to a neuro to get evaluated. You actually should have gone long ago. Hang in there and be patient.
I never got a definitive diagnosis but it was most likely a condition called Parsonage-Turner syndrome. You sound like a classic case. There really isn't anything you can do for it, other than to wait for the body to recover. I have and am back in the gym lifting weights just as I used to do. Be patient and all will be fine. Let me know if I can be of any further help to you. Take care.