Checking for food allergies

I notice that certain foods and beverages can cause--or at least make
me more prone to--breakouts. But what should be the time-lapse? I
noticed 2 small nodules Saturday night--I think. Should I blame the
onions or other salsa ingredients I had for dinner Friday? Or the
alcohol I had earlier that week--Tuesday night. How far back should
you look for triggers? And if I wanted to test certain foods/drinks
how much time should I keep track of? A few hours? The next morning?
Afternoon? 2 Days? A whole week? In particular I'm hoping to find a
form of alcohol I can enjoy without causing a breakout. But I'd hate
to blame the vodka on Tuesday for the onion of Friday's mischief.
I've also heard of clinics that test for various food allergies. How
do they do it. Over the years I've given up or tried to avoid
chocolate, dairy products, peanuts and other nuts, and salt. In
general terms, my skin IS better since I've limited my diet. But I'd
love to have some of these things back if I could be certain they
don't cause a problem.

Firstly,
"But I'd hate to blame the vodka on Tuesday for the onion of Friday's
mischief."

LMAO!

Secondly,
I am severly allergic to almonds (raw), peanuts, walnuts, bananas,
strawberries, kiwi, nectarines, peaches, and I am also lactos intolerant
(I'm a real tough broad huh?). Anyway when I eat something I'm allergic to,
the reaction is within 5 minutes. It starts as itching on the palms and in
the mouth and then I develop very large and painful welts and if I don't get
to the liquid benadryl quick, I'm dead. I don't know what the time frame is
for the breakout aspect of food allergies...I went without beer once for two
weeks and within 4 days of quitting, those little annoying under-the-skin
white things completely disappeared. Could be unrelated though...my two
cents ^_^