I volunteered for a rescue group, and we ahd many cats come in that poeple had thought they were hit by a car because they were flaling over and their head was really off balance. What the vets call it I believe is Bistibular(sp) Disease.. there is no cure and it is only life threatening in severe cases. It couses their head to tilt, and thm to go completely off balance.. I ahve seen many cats with this disease, and although there is no cure for it, the tilteed head may go away, but in most cases it remains.. but they get used to it and act as if they had it their whole life. If properly treated, the cat should hve no problem
It might just be a simple ear infection though.