Will Salicylic Acid Help The Psoriasis On The Scalp For A Child And What Could Be The Extent Of Damage?

my pediatrician did not sound like she knew much about my son's scalp condition. she pulled a book and told us it was a psorisis. i do not know much about it and what i am reading is a little scary. Talking about weak amune system and not being able to fight infections. He hardly gets sick and overall is a very healthy child. i am looking in to finding more about how to treat his condition. she gave him Salicylic Acid to treat his scalp without any instructions on how / dosage etc. Can you assist me with any informaion. a little area on top of his head has white flakes...dandroof type but it is very sticky and covers the roots of his hair in that area. when shampooed with his regular shampoo it washes away with a little vigourous combing. i was worried becasue some of the hair came off and the scalp was red and i noticed a dot of blood where the hair was grown out of... would the salicylic Acid 6% help him? Thank you.