I see you've already gotten a bunch of very helpful replies, but I'll throw in my two cents as well. :) You are definitely not alone in this. My calves are almost constantly twitching. I get frequent twitches in my thighs, feet, arms, hands, and eyes as well. At least for me, I think it's a combination of anxiety, lack of sleep, and too much caffeine––but I don't think it's a sign of anything extremely serious. In any case, twitching is a very common symptom of anxiety and I highly doubt it is anything worse than that!