I have eczema on my wrists and much less severly on my back... What exactly is the of connection IgE to eczema

My allergist says it's coffee (I was tested, I'm allergic.) My dermatologist says there's no way it's coffee. (I've been off coffee for a few days still no difference. I'll TRY to give it a month) On my wrists, it's getting pretty bad and it itches and weeps and flakes off and it's becoming unsightly. Does anyone have any expertise or a similar experience? Also could someone explain the the connection between Immunoglobulin E (IgE) and eczema. And if I can control the amount of IgE in my body can I eliminate or alleviate eczema? I've also heard that fish oils and evening primrose oils taken orally can help. Any suggestions are much appreciated.