What rash is this?

Sounds like urticaria which can be caused by numerous things. I have cold urticaria. If I go in the wind or cold, I break out in a random rash. It started on my neck and eventually ended up all over my body. Showers make it worse as does scratching. I totally sympathise with you. I was rushed to emergency because it got so bad once. Go see a dermatologist who will prescribe various treatments. I have found the absolute best to be advantan fatty ointment. It works wonders. Also they may prescribe steroids which I had but usually it comes back. Apparently there is no reason for it and it will some day just completely disappear. Mine is gone for now but I have occional flare ups. Search it for more info and good luck!