Hi, I am 33 years old and 23 weeks pregnant with my second child. I ve had a very small muscle twitch (it feels vascular, but I can see it moving) in my upper left arm, just below my shoulder, at about once per second for the past 18 hours. It s not painful, and I don t notice it if I m preoccupied, but it is annoying when I m at rest. Could it be anything of concern? Thank you!