What Causes Red Splotches And Pimples During Dialysis?

my husband is on kidney dialysis and is given Epogen and Heparin. He started dialysis on June 24, 2014. two weeks ago, he started getting a rash and kept getting worse and worse. Dialysis asked us to go to PCP who thought it may be Petechiae so he did a CBC ... came back normal. Thought husband may have an allergic reaction to Heparin given to him during dialysis. Stopped that for past two treatments; however, he is still getting red spotches and pimples now progressing to his whole body. Could he be allergic to the Epogen?