Suggest Treatment For Psoriasis On The Scalp

Hi so I have had a massive problem for the last two years or so. I have a severe case of psoriasis on my scalp which causes real bad scabbing and itching. However I have been finding black dots on my hairline and scalp. However the dots only appear after I ve been out or occasional at night or morning. Never when I m sitting at home doing nothing. I also get more when I have greasy hair. I ve read up about lice feces but I just don t know. I ve tried every lice treatment from the shampoo and conditioners, box treatments, vinegar, mouthwash, Vaseline, oils EVERYTHING!! I am using the neutrogena shampoo to clear my scalp but it s still bad and is itching like mad!! I just need help, I can t cope! What is going on? Thanks please reply someone!