Hello~It sounds like muscle spasms to me, nothing really serious as your doctor said, anxiety can sure bring this on. To relax it, try sitting in a tub with some Epsom salts, this really helps to relax all muscles and also relax you at the same time.
I'm going to say it doesn't sound like muscle spasms, as that wouldn't move around and it would have been a sharp sudden pain in one place. I'm guessing you probably tweaked something, could even happen while sleeping, or doing some form of exercise or activity or reaching. You don't say what you were doing before this happened, that might help you figure it out. There is one possibility, which is jaw clenching or TMJ, which a dentist trained in that can diagnose. Are you an anxious person? Do you regularly think anxious thoughts? The anxiety or stress would have to be pretty bad to cause this, and so I think you'd notice you were thinking very anxious thoughts. The Epsom salts bath isn't a bad idea. You might also try if you don't want to do that taking a good magnesium supplement, or eating high on the potassium and magnesium levels for a while. If it hurts when you move, you might think about getting a massage, but if you don't move and it's muscular it will get worse. If it is a cramp, just laying around will make it worse. That kind of thing responds to movement. What kind of movement is the problem without knowing where the pain is, as it's moving around. Think, what did you do just before this happened that might have triggered it?