I have dealt with muscle cramps for decades. They're very painful and debilitating. Lately, I've had warning signs. I have a repeated twitch around my left eye. Also, I can watch the back of my right hand twitch. It feels like bugs are crawling on it, but there are no bugs--just twitches. Currently, what I'm doing, I have a pile of potassium supplements on my desk. Every time I get an eye twitch, I've been taking another potassium. I have experienced a really intensely painful muscle spasm, particularly as I try to sit down.
When I was 8 years ago, I was hit in the tailbone by a boy practicing his batting stance. He hit me smack on the tailbone with his bat at full force. I was and am still thoroughly convinced the tailbone was "broken". I've studied the "normal" anatomy and mine certainly does not match "normal". Anyway, it's displaced in some manner. And the act of sitting down seems to cause a muscle in the immediate area. It seems to spasm around the "displaced" bony protrusion . I can't even begin to explain the pain. It comes on very quickly and very intensely. Horrific. But the increased potassium levels seems to help.