Scalp psorasis or Seborrheic dermatitis.

Im having red patches on my scalp and when hair grows, dandruff like white flakes forms and they easily get detached from my head scalp after i move my hand around head ive seen some small red patches on my beard skin after shaving and some white scales/flake when beard grew some time ago,also some white flaky/greasy particles in backside edge of ear skin my hair density is very low now,hairfall is very common over this period of time Im suffering from this disease for over 3 years, every doctor told me that i have some type of dermatitis (like Seborrheic dermatitis) with having medication since last 2 years from 3 diff doctors and ive got no results at all ive some symptoms over this period like feeling tired easily and constant patches of fever due to unknown reasons,I feel my prev. doctors haven't treated me well and haven't indentified whats happening to me i want to get rid of this sooner so is it really dermatitis or something else like scalp psorasis?