Help with recurring rash on temples

Every month or two I get a rash on my temples along the hairline. It happens on both sides of my head, but not normally both at the same time. The bumps look like acne or small sores, but several spots appear at the same time and then fade away together.

Here's a picture of it right now - http://imgur.com/vnWfvc6

Any ideas what this might be? I could go to a doctor about it, I suppose, but it's really just a mild annoyance.

Thanks!