I get this often, more as I get older. Usually means I need to ram more water down. Even when I'm not thirsty. Any drinks with aspartame seem to actually make it worse, despite the ridiculous amount of water that they're made with. I learned it was a water thing after it immediately following bouts of IBS, and after I started drinking a lot of Diet Coke because the gas station was running a special. And I've always had it in my jaw, often get a cramp when I yawn, then I have to hold it for about 10 seconds and wait for it to start pulsing before it eases off. Sometimes my brain says thinks my jaw is open when it's not, it's a weird sensation.
I've had this since I was a kid, happens maybe once a month too. No telling what could cause it, but my body jumps once, similar to how the TV shows shock a heart patient back to life. The jaw open thing also often accompanies this. I also don't sleep very hard and can hear everything going on around me. I can hear the circuit in my alarm clock switching right before it goes off, and will be ready to shut it off instantly.
Other than that, yes I twitch a lot. More often, I can't sit still. Feels like my skin is always crawling. Literally every 2-3 seconds, I'm scratching an itch, adjusting clothes or glasses or hair, or myself in my seat. I probably look ridiculous. I know how I looked when my dad recorded me playing on stage, often twitching as I adjusted the bass strap over and over. Not even really adjusting it (or the glasses), it's more of like breaking the surface tension then reseating it. Kinda like people would say if you keep your face that way it'll stay that way, or like images getting burned into CRT TVs.