Hi I was standing for over 40 minutes in heels on a very warm day and the top of my feet started to sweat and little red blister bumps appeared,on top of my feet a couple of days later a itchy rash appeared and stayed for about a week. I thought I had poison ivy and treated it with ivy dry, witch hazel and soaked my feet in epsom salt and oatmeal. This gave me great itch relief. Three weeks later the rash is gone and the skin has turned rough and leather like and dark colored. It still itch occasionally, but the discoloration is not going away? It never spread from the original area on top of my feet. I do take 10 mil of norvasc for my bolood pressure.