I've had this years ago when I worked midnights... I had the most awful leg cramps....very similar to what you describe.
I worked 11 hr shifts 7 days in a row on my feet, then had 7 days off.

That is when I found magnesium. It really helped. I also took 800 IU of Vit E with it back then.

So you may want to investigate a good Magnesium supplement if you don't already. Avoid magnesium oxide. If that does not work, I'd report to your doctor as you may be developing PAD or intermittent claudication.

You can soak in a tub with some epsom salts (3-4 oz in a tub) for some relief too. I know these cramps really hurt, and they can feel bruised for a day or two after even. I used to keep my heating pad plugged in next to the bed, and lie on it to help abort them. Those cramps usually happen around 4am for me or just before getting up. At that time your blood sugar is the lowest of the day. And that may contribute.

I rarely get them now. Cramps that severe are usually a warning sign. You are pretty lucky to have only had them now..I used to have them once a week or so when I was in my 40's.

Not a nice way to greet the New Year! Try some gentle heat on them and see if you feel better today.