My Two Year Old Child Bites Herself Until She Bleeds

My two year old child bites herself until she bleeds throws herself down puts her nails in her skin or puts her nails in other people's skin crys for no reason does these things for no reason if u tell her no she does it any way an I'm scared she's really going to hurt herself or someone else I don't no what to do I have other children an they never acted like that