I had all sorts of behaviors. Locked myself in the bathroom, and beat up on other kids when I was three. Ran away from home, repeatedly, when I was five. Used to grind my teeth at night. Sucked my thumb till I was a teenager. And for a long time, I used to compulsively pick the fluff off my stuffed animals. Eventually, I transferred to my own hair.
I, too, was hauled off to the doctor. Everyone thought my hair was falling out, and I was too scared to tell them otherwise. I stopped pulling out my hair after seeing the doctor. I felt too self-conscious to continue. So I went back to the stuffed animals.