Why have I got this randomly?

Today, I was in the middle of a social studies test and my face became really itchy. I refrained from itching it but then later when I looked in the mirror, it had blotchy red patches everywhere. I thought at first it was an allergic reaction, but I hasn't appeared to go away or fade yet and it is quite a few hours later. By the way, I had the chickenpox just over a week ago, could it be related to that or something? It doesn't look like shingles compared to what I have seen of that. Please can you tell me what it could be and how to relieve/reduce the rash?