Why do you really care so much about the label (name) you have to attach to your skin condition?
Does it really matter if it is psoriasis, or eczema, or Seborrheic Dermatitis , or some other dermatitis?
It is just a red light on your skin telling you one important thing:
Your liver, your intestines, your microbiota and your diet are not in good shape, you have to fix it if you want to have nice and beautiful skin.
Regardless of the label you attach to your problem, the cause is always the same, it is inside of you, it is your microbiota and your liver.
Change your diet, and it will change your microbiota. flush your liver , and it will help your microbiota.
Bring good bacetria to your intestines (home made yogurt, home made kefir, FMT, Yogurt enema) and it will help your microbiota.
Once you are cured, you will care less what name doctors would attach to your problem.
It is very possible that a different doctor would attach a different name to it.
You have the power to cure yourself.
Use that power.
You don't need diagnosis, in order to achieve complete health.
Read food labels, those labels are 100 times more important than labels your doctor would attach to your condition.