Hi, My Name Is Nancy. I Am Break Out For

Hi, My name is Nancy. I am break out for no reason. I start out with my head tingling and then it starts to stings then I get like this sun burn and break out in a rash all over my body, it swell a little. I feel like I am on fire when this happens. What is wrong with me? I take 2 Benadryl and after about 2 to 3 hours it all goes away. Can anxiety or stress cause this?