My partner used to get wicked calf and thigh cramps
He tried loads of different things - salt, extra water, more milk
Then he read one article, and thought ok... it worked for this guy, I'll give it a go.

He cut as much processed sugar out of his diet as possible... within a week, no cramps! he still has honey, fruits, milk - all with "natural" sugars.
He adds sugar to nothing and only occasionally has biscuits/cakes etc.

Good luck