I'm just seeing your question today. It would be helpful for you to challenge her to go a period of time without tbe movement (maybe 15 minutes) and see how she cope. Does she get anxious? Does she start the ritual unconciously? "Evening out" is a common concept with OCD (compelled to mirror actipns bilaterally). The sudden onset of severe OCD-like behavior warrents a trip to her doctor to rule out PANDAS (google this) or any other neurological issues.