I have a small cluster of spot type things with small holes a the top (almost like pin pricks). It is on my back slightly lower than my armpit, my skin is red around the cluster however I have been itching it occasionally (it is very mildly itchy). I have linked a photo of the cluster here: http://imgur.com/CkUDQWZ
What is it? Do I need to do anything to make them go away? Should I be concerned?