So, you did have symptoms: vomiting and diarrhea. They are classic symptoms of celiac disease. That must be why they checked you for celiac disease. A colonoscopy cannot be used to diagnose celiac disease. The scope can't reach up into the small bowel from the lower end. The kind of scoping they do to check for celiac disease is called an endoscopy. The go down into the small bowel through the mouth and the stomach. The small bowel starts where the stomach ends. During the endoscopy when checking for celiac disease, they will biopsy the lining of the small bowel and send it off to a lab for microscopic analysis. Celiac disease is an autoimmune disorder in which the ingestion of gluten causes inflammation to the lining of the small bowel. This inflammation wears down the millions of tiny finger-like projections that make up the lining. This lining is where all the nutrition is absorbed from the food we eat. As the lining becomes more and more damaged with time, the efficiency with which it can absorb nutrients becomes more and more impaired, often resulting in other medical conditions that have a nutritional deficiency cause. Osteoporosis would be a classic example but there are many others. It's important to realize that whether or not consuming gluten makes you feel ill, if you have celiac disease, damage is happing to the lining of your small bowel, however small it might be and however slowly it might be progressing. This is why it is so important for you to take gluten free eating seriously. Believe me, every celiac in the world sympathizes with you in not wanting to have to go there. Not only does it mean giving up many foods you enjoy but it also has a social cost and can even put a ding in your budget if you rely heavily on pre-prepared gluten free foods.

I had a colonoscopy and they went up to the small intestine and saw something. Prior to this I was having episodes of vomiting. It would be months apart and diarrhea would come too but always started with vomiting. Just out of the blue I would be attacked. They don't know what that is from.

Welcome to the forum, @BadHobit Were you tested for H. Pylori infection?  Sometimes this infection can cause stomach irritation and even ulcers.  H. Pylori infection can trigger Celiac Disease.  H.Pylori infection is frequently found in celiac disease. Ask for DNA testing to see if you have any of the genes seen in Celiac Disease.  Having the genes for Celiac shows you have the potential to develop Celiac Disease.  Infections, physical trauma and stressful events can trigger the Celiac genes to become active.  Symptoms appear once activated.  If you don't have any genes for Celiac Disease, then it can be ruled out, and another reason for the ulcer and Gerd should be pursued.   Stick with 4 - 6 slices of bread for the Gluten Challenge. Keep us posted on your progress!

Check with your doctor to find out if he/she wants to refer you to a GI specialist for an endoscopy/biopsy to confirm the results of the blood antibody testing or whether or not the tTG-IGA levels are high enough to grant a celiac disease diagnosis without further tests being done. If further testing is expected, you need to refrain from starting a gluten free diet or you risk sabotaging the tests.

Welcome to the forum, @BadHobit! For the biopsy they only took one sample from  the stomach and one from the small intestine? They should take several samples from the small bowel as the damage from celiac disease can be patchy. Sounds like you were the victim of poor timing with regard to each of your celiac testing experiences in the sense of being tested while being off gluten. One thing to be aware of is that once you remove gluten from your diet for a significant period of time, when you return to consuming it your reactions may be much stronger than when you were consuming it consistently. Experts in the field have recently issued revised guidelines for the "gluten challenge" as they realized that their previous advice for amounts of gluten consumed daily during the gluten challenge was not intense enough to produce valid test results consistently. They are now recommending at least 10g of gluten daily (roughly the amount in 4-6 slices of bread) for at least 2 weeks prior to either blood antibody testing or the biopsy. The rash you describe, do you think it could have been dermatitis herpetiformis?