If my feet and ankles get cold, especially when I'm sleeping, they cramp up. I usually sleep in several layers of socks for that reason, but I find taking a magnesium pill before bed helps a lot. I take the recommended dose of 135 mg of mag citrate three times a day: when I wake up, in the late afternoon, and before bed. I find that spreading it out through the day works best for me.

P.S. Avocados are a great source of potassium and magnesium, so if you like them it's good to make them a regular part of your diet.

Hope you're feeling better soon!