I Get Severe Nocturnal Foot And Leg Cramps. I Have

I get severe nocturnal foot and leg cramps. I have tried vitamins of different sorts. Nothing seems to help. I am active. The cramps come and go in clusters like fine for weeks with no cramps then many nights in a row with them. They tend to not start until I have been asleep for four or more hours. Once they start then come and go for the rest of the night. These are locking cramps. Very severe pain.