Yip I have bad cramp sometimes, It can be very painful. Along with potassium, also try magnesium.
The link below is different types of food with magnesium:
http://www.livestrong.com/article/22672-foods-contain-magnesium/
Also you can get magnesium and potassium in supplement form but talk to your doctor before buying supplements as some can interfere with medications.
Cramp can be caused by many things, vitamins are only one cause, it could be withdraws or jet lag as well or something else like MS which is a medical condition, if it doesn't get better with in a few days, i suggest seeing a doctor to rule out a medical condition.
Hope this helps
Freddie
These are normally caused by a lack of potassium. Eat a banana everyday and that should help.