believe it or not, it could be due to stess!
When I'm under stress, i can sometimes break out in hives.
Stress is a very strange thing. It seems like a harmless word, but you wouldn't believe what it can do to your body, look at ulcers.
Until you can find a doctor to dx it, I'd invest in some hydro cortizone & an alergy med to help with some of the itching.