Have you had this rash checked out, and are you sure it's a fever rash? I thought I had a fever rash, and it turns out I actually have a fungus rash. The dermatologist said it's quite common in people with auto-immune diseases and the fungus actually feeds off of sweat. 50% of the population has this chemical in their sweat that attracts this fungus. It's treated with a cream, but my dr. said that I will probably get this rash every year when it starts getting hot outside. You can treat it or not treat it, but without treating it, the rash will just spread over other parts of the body. This fungus can be picked up anywhere, door knobs, pens, you name it. My rash doesn't really itch too much. Maybe your doctor can suggest a cream that will help-like hydrocortisone cream.
Hope this helps.
"Challenges make you discover things about yourself you never really knew."
SLE and Class III Lupus Nephritis