I have Celiac disease (an inability to digest wheat, barley, rye, and a few other grains. Before I was diagnosed in 2008, I would have told you that barley was never really part of my diet, either. I'd have been very wrong, though.
Unfortunately, it's in so many different foods, it's hard to avoid. Barley malt is a flavoring used in an unbelievable number of foods, and barley (not to mention wheat) sometimes shows up as "dietary fiber", "malt", or "malt flavoring". Until very recently, Rice & Corn Chex had barley malt (they've since switched and are now gluten-free). Many, many other cereals still have barley malt, as do some chocolate candies. Its found in salad dressing, soups, etc. Some teas have barley (especially herbal teas, including some from Celestial Seasonings).
If you show a reaction to Barley, you might want to consider looking into a gluten-free diet and/or being tested for Celiac. I wasn't diagnosed until early 2008, even though I'd had symptoms for many years.
People with long-term, untreated Celiac and other dietary intolerances often develop more symptoms and more intolerances/allergies as time goes by. They begin to react to other substances (for Celiacs, common ones are corn and milk).
If you have been previously tested, it might be worth looking up which test you have had. Some tests are more accurate than others.
I had over a decade of accelerating food sensitivity, pain, rashes, digestive problems, and even easily broken bones (from being unable to process calcium) before a doctor took one look at me and told me what everyone else had missed for years.
You're in my thoughts and prayers.
My testing for celiac in its various forms has all been within the last six months.
And it’s vegetables and fruits which make me break out and react badly.