Firstly we can't prescribe, whether it's tea tree or anything else you might use on yourself we can't make suggestions like that. I would advise her to visit either GP or pharmacist but at the end of the day it will be her choice. Her best bet is to keep it clean, dry and protected until the damage grows out. Fingers crossed though that she returns with no signs of it worsening but even if that's the case I wouldn't put any colour on it so she is able to keep an eye on that infection.