Elvis, it doesn't actually sound as if your wife is actually suffering panic attacks as such. It sounds much more as if she is just getting really anxious and worked up about social occasions which is causing her sickness and diarreah.
Panic attacks are something entirely different and are quite frightening and you sort of lose control, you can't breath properly, can have chest pains, go hot and dizzy, etc. and, as I said, they happen often for no reason whatsoever.
Last time I had one I had to lean against a tree and take deep breaths. I thought I was going to pass out.