Cramp in legs

Arnica 30c, daily in the morning for 3 to 6 months, in wet dose
Mag Phos 6x, 4 tablets in 1 cup of hot water, before going to sleep for a few months. Supplies Magnesium to the body.
Cramp below knee:
Cocculus 30c followed by Nux Vomica 30c in 1 hour. Repeat once a day, most likely for 5 or 6 times, till the cramp is 80% better.
Cramp above knee:
Colocynth 30c. The above medicine could also help, if this fails.