poor circulation - try lying with you feet slightly elevated above your heart for a few minutes at a time.
try stretching out your calves and feet a few times a day.
low salt levels - even slight dehydration causes cramps too.
i have suffered foot cramps all my life and the only way i get relief is to stretch it out (even though it hurts). i tend to get them in bed at night so it means getting up and stretching it out.

i hope you get some relief ticklish.