Happens to me ALL the time, while high and sober. My entire body shakes, sometimes I shake so much I can barely walk or talk. For me it happens more often when it's cold. It feels like being extremely cold, but sometimes I'm not actually cold at the time. Usually happens when I'm going somewhere, waiting for a drug to kick in, or thinking about certain drugs. Sometimes when I'm going to my car to go somewhere I start shaking, sometimes I have to wait a few minutes before I can drive. When I take ecstasy or shrooms sometimes while I'm waiting for it to kick in I start shaking, this can usually be prevented by smoking weed right after taking something. When I talk to people about ecstasy or think about it a lot I start shaking.