What causes muscle pain primarily on left side and makes nerves hyper sensitive? had symptoms for years, usually worse in winter. also have a syrinx.

SyrinxBecomesSphinx: You have a syrinx. I presume in your spinal cord somewhere. That means you've seen at least one doctor who diagnosed it and hopefully spoke to you about it. You have some symptoms that may (may) arise from that. You've had the symptoms for years. Over those years I assume you've seen some doctors for this. So at this point, if not satisfied, I'd suggest seeing a competent neurologist in your area.