If it helps, I get that ALL the time. For me, it's usually a combination of dehydration and lack of potassium. I try to keep on top of both, but I still have trouble. And when it does happen, it's ALWAYS my calves.
Try to relax, breathe, and drink a lot of water. It helps me after a while! Hopefully you can find some relief soon, too. :)
Dx: Fibromyalgia, scoliosis, kyphosis, hypochondriasis & general anxiety
Rx: Occasional Vicodin 5, and (almost) nightly Soma. - Though I'm weaning off of these.
Calcium + D, magnesium citrate, and potassium gluconate
"Battle not with monsters lest ye become a monster, and if you gaze into the abyss, the abyss gazes also into you."