What Causes Night Quivers In Elderly Woman?

My mother in law (81yrs) says she s been having night quivers which she can t quite explain. She says it feels like her whole body is quivering and she can t get comfortable or sleep. Could this be an underlying health problem as it seems to be getting worse? She spoke to her doctor a few yes ago, who apparently just laughed and gave her no answer. She has changed doctors and will mention it in a couple of weeks when she gets a check up. I would like to know if there is any tests that she could ask her doctor to get done. Thanks.