Huge reaction from skin allergy test, OK?

I went to an allergy today and did some skin tests. The first set of tests where the liquid was just dabbed on the skin showed reactions to dust mites and grass. Then they did some sort of superficial injections on my upper arm and let it sit for 10 minutes, where I got small welts from ragweed and house dust. They rubbed benedryl on the spot and gave me a loradine tablet.

But that was 12 hours ago and now my upper arm is huge, red and hot. I have a rash/welt thing bubbled up going 2/3 the way around my arm and about four inches in height. It feels a bit tender too when I move it around a lot or press on the affected area. This huge reaction happened after I left the doctor's office. Maybe it's in my head, but the affected arm feels a bit weaker too.

Is this a problem or does this sometimes happen during allergy testing? I'm not experiencing any other problems that would make me suspect I am having a life-threatening reaction. Should I call the allergist? Should I just try some medicine?

[Tammy2009]

Call the allergist, that is a major reaction and they should know about it.  

[lovemuffin11]

Can it wait until the morning? It's midnight now. I think they'll be open at like 8 a.m. I notice it is getting bigger. I marked the outline with pen a few hours ago and it is a little bigger, like a half inch?