I have hired a nanny to take care of my 1 week old newborn baby because of her experience. However I see she rocking the baby on her lap in a fast motion which appears a bit aggressive. While she says that's normal and needs to be done while babies cry uncontrollably, I am a bit worried about shaken baby syndrome. What are this first signs / symptoms of the same ??? Is there anything to be worried about if the baby is rocked fast on a lap while sitting on the floor