In general cramps of the legs are a calcium type of a problem; many pregnany women experience sever leg cramps. You can use a 1/4 teaspoon of Epsom's salts (magnesium) to reduce the cramps as an aid, but not a cure.
The cramps usually are a result of IN-ORGANIC calcium aka LIME and or some other in-organic rock mineral problem. To experience this while fasting to me would show alot of cleansing of old hard rock being dissolved and expelled as your cleaning up.