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
I went SLS free for 4 weeks now and a lot of skin and hair problems have slowly faded away. I still get flare ups, but that was such a dramatic change.