The same exact thing happened to me when I was 15, except I couldn't move at all. I only seen one shadow and my whole room instantly became black (despite a street light being right outside my window). I too, tried to call for my mom, only finding that no noise was coming out of my mouth. I tried screaming, moving, twisting, crying, etc to no avail. Finally, I started praying and it instantly left as quick as it came. Science can't explain what happened. I don't believe it's sleep paralysis. I was wide awake and couldn't breathe. Made me have a panic attack. It was the worst feeling ever!