What Do Rashes Around Drug Injection Site On Elbow Indicate?

I have two hickey like marks on my outer forearm near my elbow and the both have been there for over a month. I used to inject drugs in/around the area, I m not sure if it has anything to do with it. It is sore at feels like it has been pinched and blood has risen to the skin except it hasn t changed size at all. What is this?