biting nipple

My LO doesn't have any teeth yet and hasn't been feeling well. For the past day every time I offer the breast she bites down HARD and rips my nipple by turning her head... I'd argue more painful than childbirth... she's done this a few times before but now it's every single feed! I've tried taking her off and giving her a stern No but nothing seems to phase her. If your LO did this how long did the phase last? Is there anything you did that worked for you?