I have myofascial pain syndrome. It's a syndrome where your muscles knot up at night when you're sleeping. The knotted muscles squeeze your nerve endings (simplified explanation) causing pain. It can be triggered by an accident --- I was involved in a car accident in early 2010. All this time, I thought it was swelling lymph nodes. Go figure.
Just knowing what it is removes much of the mystery, and --- much of the fear. It's usually not permanent, though it can last for years. I'm a good example of that. The doctor who finally diagnosed me is a rheumatologist. He said the two main ways to combat the symptoms is to take a round of ibuprofen (which I had been doing, but only when it got so bad I couldn't stand it), and muscle relaxers.
After two weeks of muscle relaxers, I feel better than I have for a long time. So good, in fact, that I'm not even taking the muscle relaxers at this present time. I'm working up to exercising every day instead of just every other day, like before. I can do things I haven't been able to do, and still sleep at night. I thank God for this every day.
My vitamin D was something like 13 points when it should have been 30 or higher. I'm also on a round of 50,000 units of D a week for two months. Since taking a month of it, my carpal tunnel (which was really De Quervain's) has nearly disappeared.
I've even been writing a little, and it's not the slogging chore it's been in the past couple of years.