I was telling someone on here last week about the problems I had when I took bicarb - and the fact it made me really vomit and I nearly passed out. Which is why I never recommend taking bicarb to do the low stomach acid test.
Anyway I've never looked it up or anything until today, and I found this link
I've only had a quick scroll but I can see that it's all back to the calcium stuff and milk alkali etc. Linked to antacids yadda, yadda
Anyway, it can, and does, happen and, as you can see, can be quite devastating.