Check with your dentist and pediatrician. Maybe allergies or teeth hurt. We did psych meds with my son and it helped. Of course, that is a personal decision for you and your kid. They make helmets as well. Some kids out grow it, I think. Hang in there.

I agree that perhaps she has something dental going on. She may be trying to cause pain elsewhere to distract her from the pain in her mouth, if that is what she is experiencing. Like I mentioned in my reply to another question, I'd try redirecting her to something soft. Hugs :)