What Causes Itchy Bumps On The Ear?

Hello, I noticed a rash of small, slightly itchy, red bumbs forming behind my ear a few days ago but figured it would go away. However it seems to be spreading to the front of my ear. Also, my ear looks very red and a little swollen but it could just appear to be swollen because it's so red. I've searched online for an answer but can't find any that sound like this.