Suggest Treatment For Itchy Rashes All Over The Body

My partner had an Extreemly itchy rash all over his body. We went to the GP yesterday however they just put it down to stress. His rash looks like someone has whipped him all over, it s red, raised and very noticeable. The nose recent development happened an hour ago, his right lower leg has become swollen and even redder. It s shiny cause the skin is so tight. I m slightly worried as its only in one leg & my partner is very healthy. He goes to the gym daily and has already gone today so he is active. Do you have any idea what could cause this to happen? Is it important enough to go to a doctor again? It cost quite a bit of money each time so we would normally only normally go it was totally necessary. We tend to like using home remedies if possible but not imperative. Some advice would be greatly appreciated, I hope to hear from you soon, Kind Regards, Sarah Lyng