Suggest Treatment For A Heat Rash On The Scrotum

my husband has what we thought was a heat rash on his scrotum. There were blisters, but they are gone..now just bumps all over his scrotum. None anywhere else. He was using powder, and jock itch spray, but it doesn t seem to be helping. He has had it now for 7 days and it isn t going away. The bumps themselves are painful. There is no pain in urine. No fluid or puss, just painful bumps on his scrotum. What should he be using? He has had cancer before, and hoping this is not some sign or symptom of some other form of cancer?