Can you please tell me what this is? I have been breaking out with a rash that will come up like a burn mark, but go back down without leaving a mark. This pops on my arms, my stomach, and chest and itch like heck. The size will be small sometimes or a huge in size. This mark looks like a rash, and it is red in color. When it goes down it does not leave a mark? It will swell my hands and feet and itch and then go back down. Now, my throat is swelling and going back down.