Do you know of any homemade, homeopathic, or store bought remedy for severe dandruff?

My husband has dermatitis, and right now he has a pretty bad outbreak on his scalp. The dermatitis is nothing new, he occasionally has outbreaks on his face, around his nose and eyebrows. I cut his hair very short tonight and I could see that his entire scalp is peeling. Where it's already peeled his scalp is pink and you can see that the rest of it is trying to flake. He's tried every dandruff shampoo (including Coal Tar Shampoo) out there and nothing seems to work. He's been using Selsun Blue Medicated Formula, but lately it hasn't been working. For awhile he had the prescription strength version of Selsun Blue, but he thought the OTC version worked better. Anyway, I'm wondering if there's some kind of remedy that we haven't tried. A barber was telling him that he should try distilled vinegar, which we just tried tonight. Or if there's a brand of natural / homeopathic shampoo that we can try from a health food store?