What Causes Itching Painful Red Bumps?

I have occasionally occurring red bumps that are only on my neck, armpits, and chest/breasts. They are raised and red, but not blisters. They hurt severely, but also itch a bit. When they occur, I also get a moderate fever (below 103, but over 101 degrees) and severe generalized body muscle aches. My right neck lymph-node is also swollen. I am also fatigued when it happens. It has happened three times since this time last year, but it has become more frequent. I went to the emergency room once and they said my white blood cell count was really high, but eventually they diagnosed me with dermatitis of unknown origin. Could I have some kind of immune deficiency?