Good luck getting a soon-ish appointment.

My DD1 has had several bouts of hair pulling/eating. I think in our case it was a comfort thing because as a baby she used to twirl my hair while breast feeding but she kept pulling so I transferred her hand to play with her own hair. She was doing it almost constantly and got a bald patch. I cut her hair short and it seemed to break the cycle. She was then fine for months but started it up again at some stage and when all else failed I cut it short again and it worked again. (BTW, by short I mean a girly bob cut, not shaved off or anything)