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
Interestingly for me my hair is much better without that, my head is more greasy and itchy when I’m using head and shoulders than when I’m using something else. I’ve switched to bar shampoo recently and been getting on really well with faith in nature shampoo bars.