What Causes A Rash On The Neck And Chest?

Last weekend I developed a rash on my neck, which also showed up around my chest here and there, it was just a rash at first than it start to feel uncomfortable after a couple of days, it seemed to get worse as the temperature got warmer. I would feel flush with a little headache. It didn t concern me to much at first but now I m feeling a congestive feeling on my chest. Like when I ve had a congestive chest cold. I m not cough or have any flu or cold symptoms. I m pretty much my normal self except for what I ve already mentioned. I take no medication, only ibuprofen when needed.