Nuetrogena coal tar shampoo.

:) DH's still got it, himself- aggravated by his wearing his thick, curly hair really, really long (waist-length, when it's wet)

the coal tar products set his scalp on fire, and he won't try them again...

apple cider vinegar (ideally the 'live' stuff from a health food store- we use Bragg's) as a scalp treatment does a great job of loosening up the crust, but he's not crazy about 'walking around smelling like a salad' which he claims even after washing his hair (I can't)

and we use coconut oil as part of a sunday deep conditioning treatment that seems to make his scalp happy enough that it doesn't overproduce oil for a few days.

if you've got the insurance, haveing someone look at it and figure out if you're having an allergic reaction to something, or if it's psorisis, or a yeast colony (DH also has rosacea, and I've found that restricting his sugar intake for a week or two does cut down on the crusties- not to mention his mood swings ;) but I can't get him to stick with it.)

Well we can't use any coal tar products. They cause a bad reaction. My skin is crawly just thinking about it. DD becomes an 8 YO drama queen when I get the apple cider vinegar out. CCS, she apparently has the same reaction you DH has, but I can't smell it either...at least after it's dried.
Hmmm...sugar you say?? You may be on to something there. Our pediatrician has had her on topical cortisone. We've also tried olive oil, special cradle cap shampoo, can't remember everything else, but nothing has worked at all. DD does LOVE her sugar, like most kids. But DS (who is 5) does not have the crusties, and eats as much sugar as DD. Maybe DD has the condition and DS doesn't?
Does coconut oil leave an oily residue? Do you apply it on dry hair, shampoo, then rinse?
Any other ideas?

:) where I come from, the drama babies have a choice- they can accept the treatments- or they can deal uncomplaining with their condition ;)

getting that through to DH was a bit of a problem...but the vinegar's a vital part of the treatment.

I'm under the impression that yes, some people 'have' it, and some people don't...and it doesn't seem to be the least bit contagious (thank gods- I think I'd kill him. my hair's not quite as long, but take pride on it being 'low-maintenance') so if you son doesn't have it, he doesn't have it.

the coconut oil doesn't leave a residue- but it's definately something that should be done the night before, and washed out the next morning.

I've also had some luck with treating it as a fungus/yeast, Melaleuca's now making an 'herbal' shampoo with tea tree oil in it, and I add lavander oil to it, as well.

did the cortizone help the scale? or just reduce the irritation?