Contact dermatitis or FOOD Allergy reaction??

I started noticing itchiness on my jawline/neck and wrists. Over the course of a 2 or 3 day period, it grew worse and worse, till I developed an intense itchy, red rash over my entire neck (front and back), red itchy dots on my wrists, extremely itchy eyelids, earlobes, mustache area, and entire area under the chin. Also, a horrible red itchy rash in the groin area.
I am on prednisone to cure it. One doc said possible food allergy; other doc said contact dermatitis.

1.) Based on the facts, was this probably caused by a FOOD that I ate (a food allergy), or something I came in contact with in the environment (contact dermatitis)?

2.) With contact dermatitis, does the substance literally TOUCH every part of the body that gets the rash/itchiness? Because I'm telling you -- NOTHING (to my knowledge) touched both of my eyelids and earlobes, under chin area, and entire neck etc. In other words, nothing I can think of "contacted" all those parts of my body. (And I've used the same products at home my entire life.)

3.) I had dental work done previous to this.. is it likely to get such a reaction from something done during dental work?

Any thoughts / suggestions would be appreciated....

thank you

When you say "transferred".. I'm trying to understand how that works. If I touch one part of my neck with a substance I'm allergic to, can it "spread" by itself to all other parts of the neck, and up to the eyes, earlobes, etc? Is that how it works..?

Oh, that sounds like so much work, but we don't have a choice if we want to find out the culprit. Everything -- our food, soaps, bathroom cleaning products -- EVERYTHING becomes a suspect. It's overwhelming.

I live in an apartment and therefore use a public washer and dryer. So whatever softener sheets the person in front of me is using -- I am probably being affected by them to some degree.

I have not switched any products -- but what if these companies change the formulas for various products? that is always a possibility!

I guess I need to start the long, tedious investigative journey to try and figure this out.. because I don't want this to continue happening.

And you probably can't get a second rinse cycle either unless you pay for a whole extra wash.
Might try smelling the machines for perfume before using and wiping them out with a paper towel.

Stop using anything with perfume or color in it. I use just a little vinegar in water for cleaning most things. I have good luck with Neutrogena soap and shampoo. Watch the moisturizers and lotions too.

Yes, keeping a log is work, but it's really not so bad if you just leave it on the kitchen counter. It paid off big for me - found sulfites were triggering my reflux and tachycardia.