I thought I was alone
I have the same problem!!
Back when I used to 'poo and co everyday, I would straighten quite often too- I wanted it to stay straight so I'd not wash my hair for a couple of days in a row. My scalp would get SOOO ITCHY and of course, the more I scratched, the more it itched. I've been no 'poo for a while now, but it still gets itchy every so often and that nasty white oily stuff is annoying as all hell to me.
What's worked for me is: I use Head and Shoulders Intensive Treatment when the itchy gets extreme- it used to be about once a week, but now it's maybe every two weeks- the bottle I have has lasted me about a year and a half. And when I condition and put products in, I try my best not to apply them to my scalp. And of course the more I scratch, the more it itches, so I keep my nails away from my head!
I feel your SD pain ... good luck in whatever path you choose to treat it!