Seborrhea in my scalp is very itchy and embarrassing Ive try medicated creams and shampoos, it allways comes?

I have big white crusts in my scalp, please if someone knows how can I treat it.Seborrhea in my scalp is very itchy and embarrassing Ive try medicated creams and shampoos, it allways comes?
I had the same problem for years and you may not get the same results but I found that it was an internal problem for me, it was so simple. For me it was dehydration not drinking enough water and also I think good cholesterol helps such as found in fish oil I take Omega-3 soft-gels hope this is help full.