I totally sympathise.
I was the kid that got head lice for 9 months straight in HIGH SCHOOL.
Alphabetically my locker was always next to the same girl every year. And this particular year, she had hair lice.
I was using K24 hair shampoo almost every 2nd day, my hair was a complete mess. I was also dying my hair every month which would completely destroy them. I got to a point where I cried to my Mum to try and convince her to shave my head. I was over being infested.
The amount of times I pleaded something to be done about this girl, they simply turned a blind eye.