Vibrating noise from freezer/fridge?

Question

I have had a GE fridge for 2 years. Refrigerator on bottom and freezer on top. Last week a noise started, sounds like regular "running" noise but louder. And 2 times it is incredibly loud. Does not stop when doors are opened. Louder when freezer door is opened. When touch back wall of freezer sound "changes". Please help its driving me nuts!