Talk to Dermatologist on Dandruff And Itchy Oily Scalp

I am facing this issue on and off for years now. at times a shampoo doesn't suit or sth and I get dandruff and itch. that doesn't resolve for long. I have oily scalp. earlier I used to wash hair daily because of oiliness. with time I learned washing on alternate days and how it'd improve the oily status. I did improve and I shampoo on alternate days but now I'm again facing dandruff. it gets so itchy that my scalp start bleeding and crusts form at places.please recommend something.