Is it normal to shiver violently when i cry?

I am 20 years old.. not an age where any of this is normal, I know.

Sometimes I wake up in the morning in a sort of fit- I'll start crying the moment I wake up and not stop for an hour, sometimes several. I'm not particularly upset when this happens, my mind tends to wander to random things but at the same time, my body is going through all the motions of crying very hard. The strangest thing is, I often shake violently during these episodes. Sometimes if I concentrate on relaxing my muscles I can stop or dampen the shaking, but as soon as I lose focus I'll be back to trembling. This lasts as long as the crying does. Is this normal?