Turns out washing your head with shampoo twice and blow drying afterwards fixes my itchy scalp. Don’t ask me why, I don’t know. I just know that since my hairdresser did that, I feel so much better.
Thought I’d spread the word, because it is so frustratingly simple :D
For me it was just to stop using shampoo. Keep it short, rinse it a couple times a week. Maybe some Bronner’s soap once a month. Now it seems weird that I would have ever used shampoo and/or conditioner.