I have the same thing!!! I am 29 and I have had it for about 5 years now. I have never really been a burper - I can't make myself burp and usually the only time I do is if it sneaks out (mostly while yawning, stretching or vomiting) and it hurts sometimes!
I thought it was soda but I get it when I drink other liquids too so I am not sure the cause of it. I have tried cutting things out, one at a time or a bunch at once, and nothing seems to help. I too also went to the doctor and asked about it and was also told it was just that I take in air when I eat - well hello sherlock - we all do. It is embarassing, I refer to it as "calling dinosaurs" because sometimes it is SO loud and I can't stop it. It just has to come out. It usually lasts anywhere between a half hour sometimes up to 4 hours before I feel any relief. I feel bloated, like everything is just sitting in my stomach and it won't go anywhere. Most of the time I can feel the bubble coming so I try to push it out if I am at home or in a place where no one is around - this seems to push out more than if it you let it come out on it's own and this seems to help but it sounds terrible when it happens.
I have never met anyone else who had this condition so I am glad I am not the only one!
If anyone does get a real answer from their doctor I would love to know what they say it is but it just doesn't seem to be anything that doctors are too concerned with. I hate it, it's socially crippling. You can't go out in public after eating because its so loud everyone can hear it. It concerns me because it is so loud but I don't get it all the time but usually after eating and mostly at work which is even worse
I have tried a few things, right now Gas-X seems to help a little. I take it after it starts and it goes away quicker or I chew mint gum - it is supposed to supress the acid in your stomach and it seems to help a little but lately not so much anymore.
It is very embarassing, it makes me feel very uncomfortable and I want it to go away. I am getting married in September and the last thing I want to do is gurgle while I am thanking my guests for coming. I know it sounds silly but I am almost afraid to eat or drink anything that day!
If anyone finds anything out, please share - I will be forever grateful!