That's pretty extreme self harming you are describing. I would be going to a GP and give all the history and facts and show what she is doing to herself on her body, especially after this recent episode, she would have obvious marks I assume.
I have heard of of head banging, breath holding and pulling out of eyelashes and eyebrows and all of these needed a few consultations with either an OT or Child Psychologist or both. The other thing to come out of it is they may help and show you how to deal and cope with it as well.
She sounds very frustrated that she can't express herself enough even though she has great vocabularly. They just don't understand their feelings and how to deal with them.

GL xxx