I've had this problem on and off for 20+ years. It's not like normal dandruff, just large flakes, sometimes a bit scabby, where my hair meets my neck (& used to get it on my forehead hairline too, thankfully haven't had it there for years). Sometimes it goes away for a year or two but always comes back until I find another product that works.
I've tried a few products over the years - hair masks, lotions, etc. Most recently I've been using body shop ginger, which worked for a couple of years. I thought I'd finally found the right product, so bought some black jumpers - big mistake as I can't wear them now it's come back.
Has anyone found a product that works for this? Lotion, shampoo, vitamins, diet, I'll try anything. It really affects my confidence. I was looking forward to getting a haircut when hairdressers reopen, but I just want to curl up and hide when my scalp's like this.