Hi guys I was wondering if you can help me.

I've been wondering why I do this weird thing with my hair since I the
age of 13 and now i'm almost 21.

sometimes when I'm nervous(only in my house) I sometimes pull a piece
of my hair and bite it with the front of my teeth,(BUT I DO NOT EAT IT)
I just put it in my mouth and then throw it on the floor, and I
randomnly read online thats its a Zinc deficiency?? I've also noticed
several spots on my fingernails..

I only do this when I'm bored and I have nothing else to do. (When I
feel nervous or anxious)
Never at work or school. My grandmother and my parents keep on asking
me why I do that but I cant help it. I might stop for a minute or two
and then it will come back.

I do not have any medical history of any problems. I am a health 21
year old, with occasional anxiety. I do not take any medications at
all,...

How do I go about telling this to my doctor, I am a little embarassed
and I do not want her to think I have some kind of psychological
disorder.