This scared the sh*t out of me!

A couple hours ago just before I went to sleep, according to my older sister my body suddenly spazzed and in my it felt like I was being crushed. As soon as I felt that a bunch of images of people I didn't recognize we're suddenly hit by a semi-truck in their vehicle. I don't know what or where this was I saw it all as a backseat passenger and when vehicle got hit it felt I was flew forwards into the back of the driver's seat and some voice whispered loudly. "Death." My sister woke me up because the way my body had spazzed scarred her. I'm kinda freaking out because this has never happened before and I don't know what to do.