My 13 Year Old Son Woke Up With A Small

My 13 year old son woke up with a small bump on the left side of his head about 3 inches above his eyebrow, under his hair about 4 days ago. This morning he woke up with another one on the right side of his head in about the same position, but on the right side. The bump on the left side is now red and looks almost like a blister. He has no fever or headache, and the bumps only hurt when they are touched. Should I bring him in to his doctor, or is this something that is relatively normal and will go away on it's own? Thanks for your help.