TCP for scalp infection/scalp odor/smell hair syndrome:
Use TCP which you can get from most pharmacies/chemists depending on where you live (I found it in the mouthwash aisle). Cover your scalp in TCP and let it soak under a shower cap for a few hours, then wash it off with normal shampoo.
Side effect - your head will smell like TCP for about a week. This is a strong disinfectant smell but not a horrible smell. So it's better to do this on a weekend or when you will be seeing less people. The smell of TCP will fade with time and the infection on your scalp that causes odor will be gone.