if its cos you've got dandruff/dry scalp then use Head and Shoulders.
If you think it might be lice then what you can do is get someone to check your head.
a fully grown adult louse looks like this:
They are typically about 2-3 millimetres long. Also, look for little brown eggs stuck to your hair about 1 cm from your scalp.
Typically, you'll find most of them around the ears and the back of your head.