Agree with whats been posted already, just want to add:
maybe try adding a taruine supplement for a couple of weeks, see if that makes a difference. Just a thought.
Taurine will definitely help. My girlfriend used to get foot cramps a lot, I put her on cal/mag, had her drink fluids, eat something with sodium and take taurine. The taurine helps absorb the other nutrients and keep your muscles from cramping up.
Heres some info I have saved in my supp docs folder (forget where I got it all from, probably on here somewhere or BB com):
-Taurine: Taurine is an amino sulfonic acid that is found in high levels in the skeletal and heart muscles of humans,as well as in white blood cells, and the central nervous system. Taurine aids the movement of potassium, sodium, calcium, and magnesium in and out of cells and thus helps generate nerve impulses.
Muscle pumps/cramping occurs when there is a disruption of the movement of these electrolytes in and out of muscle cells. See below for a more detailed explanation of the pathway. Dosing: (5-6) grams/daily can be taken to help limit excessive muscle pumps/cramping that may occur. I recommend dosing both pre(3 grams)/post(3 grams)workout.
-Fluid/electrolyte intake: It is also very important that you keep your fluid and electrolyte (sodium,potassium,c alcium,magnesium) intake very sufficient throughout the day. Fluid/electrolyte loss through training depletes interstitial fluids (basically the fluid that lies outside of the cells) which also attributes to muscle pump/cramping issues, and here's how:
Painful muscle pumps/cramps occur due to loss of the osmotically active particles (mainly NaCL or salt) outside the cell within the interstitial spaces. This causes a disturbance in the osmotic balance (pull) of fluid moving in and out of muscle cells. This then results in muscle cells excessively swelling (because they contain more osmotically active particles and fluid) and you develop very painful pumps.
This process can also lead to problems with the calcium pump inside muscle cells. This will cause VERY painful cramps due to the muscle being locked in a contractive state. This is why adequate fluid and electrolye intake during training is very important to maintain this balance and prevent these issues.