Vitamin E is my third remedy when cramping is involved; after magnesium and salt. Often overlooked. I would go for the natural E`s; as there are different tocopherols; and the syntetic version dont work so well.
I used it when pregnant and never had cramping.
google vit E cramping you will find several studies and testemonies.
"A clinical investigation into the therapeutic value of vitamin E (tocopherol) in certain dermatological conditions of obscure etiology led to the incidental observation that this compound produced beneficial effects in some of the patients who were suffering from frequent and severe nocturnal leg cramps. Nearly all of the patients with leg cramps received prompt and gratifying relief from their symptoms while taking vitamin E"