I Have A Rash That Started Three Weeks Ago With

I have a rash that started three weeks ago with one circle shaped small spot, then several started under right arm then left arm, next week they started spreading to the back of my legs now going down the back of the legs, and now down the inside of my arms and into my palms and fingers. I have a pain in my right shoulder and arm like I have hurt it, but when I move my arm to reach to my back it burns. Three weeks, only right side very mild itching. I'm using calamine lotion. Day before yesterday I had vomiting and high fever, only lasted 24 hrs. Wasn't sure if it's all related. Your thoughts?