I do not know if I am reading your question correctly. If you mean that she just stands there and rolls her head back and forth or do you mean that she is doing it in a playful manner for fun/attention? I know that out dogs love to flop around on the fooor and roll their heads around just for fun. She may be trying to initiate play with you. If you suspect it is stemming from something more serious, say neurological, then I would make an appointment with my vet. Best of luck!!