Dandruff? Or something else?

Hi I have itchy,irritated scalp after washing it ONE DAY!!! I have natural hair so I can’t wash my hair everyday or else it’s dry. Sometimes my scalp gets so picky and itchy I can’t handle it. I scratched off my scalp and it came off in large brown/transparent flakes. Can someone help me know what this is? I also have eczema if that helps. I plan on going to my doctor soon.