I find that really hard to believe, to be honest... maybe your EC is very different to mine, but quite a few doctors have seen my EC and noone has ever seen anything like it. And your derm claims to see 3-4 a week? Hmm..
Did he/she say how many of them he/she was able to cure or even help?
Also, considering that I can't remember even one case report where an EC patient was cured after their derm finding an allergy, I find it odd that allergy testing would be the first thing to do. Although it's pretty much the easiest thing to do, so that might be a reason.
But good luck anyway. I'm not saying it can't be true, just seems strange to me.