Redness swelling upper left arm, it is warm to the touch, swollen, very painful and know it is starting to itch, and now I am getting the same thing in my abdominal and left breast. I went to the dr on tues he put me on 500mg cephalexin 3x a day. I have been tacking that but feel worse tonight with the pain an itching in left arm, aches all over and nausea. I also notice my arm is getting deep purple under skin. I have had mersa in my lungs about 4 yrs ago, was hospitalized. I am getting worried thats whats happening not sure what to do if I am just over reacting