If the B12 doesn't work out, food intolerances are worth looking at. Food can cause problems like this: https://health.google.com/health/ref/Celiac+disease+-+sp

If the B12 doesn't work out, food intolerances are worth looking at. Food can cause problems like this: https://health.google.com/health/ref/Celiac+disease+-+sprue https://health.google.com/health/ref/Celiac+disease+-+sprue That's one autoimmune disease caused by one specific protein found in wheat. Suppose you have a similar problem. You could fix it by cutting out the offending food. Wheat would be a good thing to start with. My wife cut it out (along with sugar) and found that her lifelong GERD went away. That's not in any standard medical advice. It's worth a try.