It's horrible, there's nothing that really helps. About 7 years ago I developed a rash that would shift to different parts of the body, but it would always be symmetrical, left forearm then right forearm, right foot then left foot, and both butt cheeks at one stage

. My doctor started running tests, telling me all the scary things it could be he eventually sent me to a skin specialist when he couldn't figure it out. The specialist examined me for maybe 10 minutes, then asked me if I had a cold just before the rash appeared, which I had, and he said the cold virus is still in my system, and I'm mildly allergic to it, and it will take months to clear up, in my case about 18 months, I didn't even notice when it was gone, I just wasn't itchy anymore. Treatment was a quadruple dose of antihistamines every day, if the allowed dose was 2 tablets I could have 8, to reduce the itching, also cool baths and showers were good.