An increase in acidity and an increase in the amount of stomach acid in the stomach are not one in the same.

The best thing to do is to not stop eating things like garlic and onions but to decrease the portion size of those things and to eat them in moderation.

I suggest you learn how to eat a balanced diet. Learn how to eat properly as a vegetarian. Have a look at the vegan food pyramid: http://www.chooseveg.com/vegan-food-pyramid.asp

Lastly, the rumbling sound if its not followed by some type of heart burn can be you just being hungry. You are consuming significantly less calories not eating meat anymore. As to the endoscopy, that is probably your doctor just ruling out any gastro problems.

Plants generally take longer to digest/process due to their tough-to-digest cellulose, fiber, increased amount of extractable nutrients, etc. Most herbivores have longer, more complex digestive systems (Google the digestive systems of cows or even sheep) to help extract more nutrients and help break down the cellulose and fiber.

Maybe some of the things I just said weren’t scientifically dead on, but I’m guessing you are just getting used to vegetarianism. Your body is adjusting to your sudden diet change. Give it some time to adjust and you’ll likely have less stomach pains then you did from before you made the switch.

Or alternatively, after cutting out meat from your diet, you’ve been eating increased amounts of high-acid foods (like tomatoes) and that may play a more important role (or you could be depriving yourself of non-sidedishes could just be hungry). Try breathing more deeply around the time of meals and chew your food slowly instead of eating so fastly you hardly chew or breathe (which most people including myself can be found guilty for). If you can isolate the cause of your heartburn, lay off of that food for a while or dramatically decrease consumption. According to this site (http://www.stop-heartburn-indigestion.com/natural-antacids.html ), dietary fiber, bananas, milk and other dairy products can be effective natural antacids for some people. The dairy is obviously invalidated if you have cut dairy out of your diet also, but increased dietary fiber and bananas to your diet might help . You could also try some antacids or medication (like, say, TUMS) and see if that helps if all else fails.

Hope I helped