I have a similar issue with "electrical shock like" twitching followed by severe cramping but only when I play tennis . It always starts in my calf and then it cramps or becomes sore/weak. Sometimes it goes to my Quad. Its happened around 3-4 USTA matches , very random too I can play for hours one time and other times its halfway thru. I feel like I always prepare beforehand with hydration and magnesium/potassium and electrolytes, etc but its scary and never happened prior to my 40s