-In the outside of both of my upper arms near the rotator cuffs.
-In the upper back near the rotator cuffs on both the sides of my upper back.
-Below both the pecs, in both sides of my rib cage, to the left and right side of my solar plexus. It happens more on the left side than the right side.
-In my left lower arm, near my left wrist. But this happens only when I am sleeping on my stomach and I put the left arm under the pillow. I guess this one is definitely some blood circulation/muscle twitching thing.