I'm Trying To Decide Whether To Go To The ER

I'm trying to decide whether to go to the ER or not. I have a rash that is covering the majority of my body. My eyelids are swollen and the rash is even on my palms. I have seen three doctors regarding this rash and they have given me rash creams and steroids but none of this has helped. They did a biopsy and said it's an allergy but I've been to an allergist and nothing is helping. There was also cytoplasmic fluorescence found in my blood with a cause "unknown". I don't know what to do. Should I visit the ER or is there a specific doctor other than an allergist or dermatologist that I should see?