I agree with jellokelli, if you haven't been diagnosed with celiac then why would this herbalist do this. First, get checked out on what you are actually allergic to by an allergy specialist that will run tests. A Gastroenterologist is the guy that checks out your stomac, and digestive organs to make sure there isn't anything more serious.
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The herbalist is on the fad kick of no gluten, but it doesn't mean that "you" are allergic so may be the way to go. I think that a allergy specialist followed a gastroenterologist and then a nutritionist would greatly help to get you on a proper meal plan with what you can actually eat.
I also have Sjogren's and I have auto-immune pancreatitis as a result and have my gall-bladder taken out too. The gastro found out what was actually wrong with pain in my sternum. They do the scope down the throat to take a look at everything, was a good thing too. I had ulcers, pancreatitis and gall bladder problems. You may have to have a CT scan or even a MRI if your symptoms persist and don't resolve and is causing you great pain or discomfort like it did me. If you are not that bad at the moment with time your symptoms will get worse if you are in doubt about the area or what it may be.
You were saying that you have never been bothered by food which is good. Ask yourself, how does your face look? Do you have a persistent rash? Do you have the dry skin we usually have? Are you getting cracked lips, which is a sure sign of dehydration?
Pay close attention to your digestive organs, back pain, sternum pain, diarriah and or constipation consistency....
No Gluten is usually associated with Celiac Disease but can also be related to Sjogrens. Have you been diagnosed with this? If not maybe the herbologist is trying to rule out other problems before diagnosis.