One possibility i would consider is that intermittently the nerves or blood vessels or both may be getting compressed in the cervical spine
in a particular head position. This can cause the transient symptoms of the type that you described. History of fall and injury
in the past that you had favours this. Another possibility, which is less likely is that these are minor seizures. You chould definitely get evaluated by a neurologist
and treatment may be planned after finding the cause.