Hi Julie, I used to have horrible charley-horses, which are muscle spasms that can be seen as the muscle cramps under the skin. I learned two things by asking every doctor who would listen.
First, these spasms are usually the result of a potassium deficiency. Eating a banana every day provided enough potassium to settle the muscles.
And second, when you're having a spasm, knead the muscles with your hands as hard as possible, as if you were unbraiding the muscles strands, which are knotting tight together. It'll hurt like hell, but it works. Pushing fingers into the muscle mass as deeply as possible at the same time works with unknotting as well.
Potassium, deep muscle massage. It works.
Let me know if you try this.