Cramp in calf muscle happen due to exposure to extreme cold climate, reduce blood circulation, less water intake, muscle weakness, overuse injury, or vitamin B deficiency. Now in your case you have to check are you expose to cold climate for long time recently? Are you experiencing pain while squeezing calf muscle bell? If yes then could be related to circulation and you need to do dopler test and visit the physician, do you take less then 3 liter water a day? If yes then improve water intake, do you have recently participated in any running or cycling activity or is your job keeps you always standing and running here and there? If yes then make sure you get some time to relax yourself in between, next and last do you have vitamin B deficiency if yes then take some natural supplement for it. Now apart from this to deal with calf muscle pain you can also deep your leg in hot water, use a crepbandage with light pressure. And do some calf muscle stretch frequently to reduce the frequency of Cramp. Take care