I had severe back pain with spasms that had me almost completely immobilized a few weeks ago. It might have been a pinched something, but I don't know. Sometimes I get a virus that settles into muscle groups causing a lot of pain. This last episode felt a lot like that, but it didn't respond to my normal way of treating this virus. It went away gradually, and it's completely gone now.
The virus I experience is very similar to the one that causes shingles, and it can flare up from time to time in any number of places, including in my head and the area around my spinal cord, causing all kinds of problems from migraines and vertigo, to flu-like symptoms, and a bunch of other problems, including the intense spasmic pain in some muscle groups (and one time even in my digestive tract).
The best treatment I've found for this virus is a tincture of the herb, Chaparral. I get the best results from a brand called "Quantum", and I take 30 drops in a large glass of water (the stuff tastes awful), several times a day as needed.
Unfortunately, I find that flare-ups of this virus can be caused by eating: chocolate, corn, peanut butter, monosodium glutamate, and also by drinking alcohol. Sucks, but the virus is worse than going without those things.
If you try some of the Chaparral, and your pain goes away, there's a chance that your problem is of this sort (although there's no way to know from just one experience since the pain could just go away by itself anyway). But I find if I start taking the Chaparral right away when I start experiencing this sort of thing, it usually goes away within a day or two. And if I don't, it often lasts for weeks.