I was in your position, I had Acne and then I got Seborrheic Dermatitis .... Tried everything, like you listed... I thought....
After 4 years I suddenly came to a Chinese acupuncture. He felt my pulse looked at my tongue. There is a imbalance in your liver.
To be clear I tried raw food, Liver Cleanses f*cking "everything" but this guy solved my problem! for the first time it all cleared up after 6 treatments.
You have to find a really good chinese doctor that knows what he/she is doing! I promise you there is a solution. BUT of course diet and lifestyle is very important. But after he solved my problems I could eat many things again! Good luck!