I think that I have psoriasis on my scalp. It is scaly, tender, red, extremely itchy, and scabby. No dandruff shampoo has ever worked either. How do I stop the itching? It keeps me up at night and is kind of embarrassing since I have very dark hair. Tea tree oil has slightly helped, but old for a few hours. Is it psoriasis? And what can I do to treat it?