I had an experience with an active rugby player,
he gets cramp in his legs at night when sleeping on bed.
Due he is generally fit and strong, no strengthening program was given

But, I have found that there's a decrease in his ankel range of motion
and pain were felt at the end range of knee flexion.
I have thus givening him some soft tissue treatments - e.g massage
and some stretching exercises for the calf muscles.
he found pain were better after 2~3 treatments

If his presentation is similar with your, just in different area
you may try to give yourself some good stretches.
Dosage: 10~15sec hold x 5 times x 2~3 set/day

Hope that helps, otherwise, better get a physician to check out for you