Leg cramps could tie back to sodium, potassium, or magnesium. You should be supplementing all 3.

From "The Art and Science of Low Carbohydrate Living"

Low carb diets are natriuretic - they make the kidneys dump sodium. Sodium deficiency can cause headache, dizziness and fatigue. With continued low carb intake and sodium restriction, at some point your kidneys start to excrete potassium in order to conserve sodium. Potassium deficiency can lead to muscle cramps, cardiac dysrythmia. it can also cause the body to lose muscle, even when there's plenty of protein in the diet.

So potassium is likely the immediate issue, but it's likely caused by an underlying sodium deficiency. Magnesium is also key for absorption of potassium.

So for leg cramps, the first thing I would do would be to get some sodium in your system. Drink a cup of broth. I use a bouillon cube in hot water. You should be getting 3-5 grams of sodium per day when you start low carb / keto.

Broccoli, spinach, cauliflower, avocado, salmon and mushrooms are all great sources for potassium Lite Salt is also a good option, as it has both sodium and potassium. For magnesium, I like Slo-Mag. I also like Salt Stick, which are capsules you can take with Sodium, Potassium, and magnesium in the amounts you lose during exercise.