Re: Sudden itchy throat, roof of mouth, sneezing and stress?
Well, dust mites are everywhere. And stress can affect the immune system. By atmospheric allergies do you mean pollen? Because dust plus pollens would generally be enough allergies to make getting shots worthwhile.
I've seen it several times in myself, that I'm being exposed to something I'm allergic to, but getting only mild, barely noticeable allergy symptoms. Then suddenly a switch is thrown, either exposure passes some invisible threshold or my body changes a bit, and I'll be sneezing so hard I can barely talk, or one patch of itchy skin is spreading like a fire over my whole body. It's generally NOT as sudden as you describe, but it can happen.