Yikes! You could try numbing her gums before you nurse by giving her an ice cube in a washcloth to chew on. You might also want to try some Hyland's teething tablets or homeopathic chamomilla just before nursing. If she does clamp down and pull (ow!), I'd unlatch her and offer her something else to chew on.
Hope you get some relief soon!
Hope you get some relief soon!