What Does Bumps On An Arm Mean?

Hello, I have two bumps on the same arm; one located on the back of my forearm and one on the inside of my upper arm. They both itch and are pinkish. They are just smaller than a quarter inch and are a perfect circle, kind of looks similar to a blister but there is not any puss or anything coming out. What could it be? They have been there for about a week and have not shrunk.