You could be looking at vestibular disease which could be caused by a problem with the inner ear or an abnormality within the brain. This would put the cat off balance , show falling, incoordination , and possible rapid eye movement. Treatment will depend on the cause. If this is idiopathic, no known cause, then it will probably go away on its own.
I would bring the cat in for a check up of the ears. Here is more on this.