That's hives if you don't know Latin. I get it once in a while; I've never bothered to find out exactly what causes it. The best that the dermatologists could tell me was, "It's probably something you ate". I usually get it on an arm or near my chest, it itches for 2-3 weeks, spreads to the immediate vicinity, and then it goes away.
A week ago I got it in the small of my back. It's spreading to where it's embarassing to scratch.
This is the last time I write in here about skin conditions.