I had an employee allergic to her own hair, caused by the death of her doggie at about age 3 or 4. Very traumatic to kids. I've had grown men cry as I took them back in time to a similar event. Nothing to be ashamed of. It's the way we're made.
Ongoing stresses are very difficult to deal with.
I'm not so skilled there. I believe you have to get out of the stress-provoking situation or have an attitude change about it. I fixed a 30 some year old man of lifelong fingernail biting. Took maybe 15 seconds. I believe it was his stern father.