HELP!! My 3 year old will not stop biting her nails...? She bites then until they are bleeding and sore.?

then she also bites on her fingers right above her cuticals and she sometimes will have a hugh bump there from biting on it it. I fell so bad when she is crying because her fingers are hurting but also i am getting frusterated with the constant reminders. I have to tell her a million times a day to get her hands outta her mouth. She has recently been on a "germaphobe" kick and quickly stops biting when i remind her that there are so many germs in her hands. I am affraid that if i dont break this habit soon she may do it forever... ANY IDEAS?? plz :)