I know I freaked too. Feels like baby is having a seizure :/
It feels like I have a vibrating phone inside. It happens to me too!
Thnx.I kinda freaked out fr a minute it looks crazy when u see it and feel it I thought something was wrong
My daughter does that all the time. I went in and asked my doctor about it he said it's normal and when baby moves all arms,legs,head, and back the sac shakes like that.