Are you diagnosed with Psoriasis by a doctor?
My mother had Psoriasis on her scalp and other places, and a homeopath cured her with 1 dose of Psorinum 200. The homeopath said that when it works, 1 dose should suffice, and she'd be healed in less than 2 months. In no case should she take more than 1 dose, and shouldn't drink coffee until cured because that makes the Psorinum ineffective.
Obviously, this isn't medical advice, just somebody's story ...
I'd suggest that you contact a homeopath, or / and look up a forum frequented by homeopaths and ask there.
Everything expressed here is what I believe. Keep that in mind when you read my post, as I kept it in mind when I wrote it. I don't parrot others. Most of my spiritual beliefs come from direct channeling guidance. I have no interest in arguing whose belief is right, and whose is wrong. I'm here just to express my opinions, and read about others'.