Taking a Benadryl should clear them up almost immediately. I only use children's because I don't like the sedating effect. How about a cool shower, did that have any effect (anything lasting on your skin would get washed away)

I use to get them all the time at night just before bed from contact with my previous cat. Before that, I have contact dermatitis to nickel and once merely tried on a pair of sunglasses with metal frames for a few seconds (the nickel lobby's slogan is "a little nickle in everything") and had a welt across my nose for three days!

I think hives can be aggrevated by being aggrevated about them :-) Medline says infection and stress can cause them as well as drug or food allergic reaction. I know I've gone to bed with hives and they've been gone by the time I've awakened but seem to take longer if I "mess with" them.