Hi A.,
I don't wish to alarm you but are you sure that your baby is having a chill, or is she having a seizure? Is there any change in facial expression or loss of body control when she does this? If this happens multiple times a day and it's been happening for months, I would have made an appointment to speak with the doctor about it by now, if you have not. While I surely am not a doctor, can't diagnose something and it may be (hopefully) nothing serious at all, any health concerns should always be directed to your baby's doctor. Good luck and I hope its nothing to worry about at all!