When was the surgery? Sometimes they aggravate a nerve and there's a big one that runs down along the outside of the jaw that can be easily irritated. It just takes time to allow for healing. Nerves heal much slower than other tissues in the body...they take months when other areas heal in weeks.
Tell your friend that it takes time and to protect that area from cold or wind until it feels better. And you can always check with the surgeon on how long it should take to go away. Botox might be able to be used to deaden the nerve if necessary for a short period of time but may have unwanted side effects.
Good luck.
