Well, I don't know if this is the same thing you are describing, but I went through a period of time when I 'vibrated'. Literally...it was not just the feeling of it...it was visible. When I laid down on the bed, the bed would shake from my vibrating body. I felt like I was standing next to the spin cycle of a washing machine...or a jackhammer. I went to the ER one night because it was so violent it scared me. I had all kinds of testing done and they said it was just anxiety. Like you...these attacks were not constant but seemed to really kick if when I tried to relax.
I remember one night I was laying on the couch, the vibrating started and I watched a vase on a table across the room shake with the 'pulses' I was sending. Who would believe this kind of thing could happen...
It went away...knock on wood!
Donna