Since I have cut animal products out of my diet the burps have not come back! Any animal protien but especially red meats and dairy! I know this post is old but hopefully it helps (:
You may have food sensitivities you weren't aware of before. I would see a naturopath and try a food elimination diet. This is one of the best ways to identifying food sensitivities. There was some talk about Fruit Malabsorption Syndrome in posts I've read in the past. A naturopath can help you figure out which foods are bothering you and can help you whether it's food sensitivities in general or the ones associated with Fruit Malabsorption Syndrome. From what I read, there are more foods involved with this syndrome than you might expect. Some you wouldn't expect to be on such a list at all.
Food sensitivities can be delayed reactions from several days ago even. Can you remember eating anything different from your usual three or four days ago? I'm not sure what the longest delay is, but this is a reasonable place to start, because it is at a usual range. But, there can be delays that are longer than this. A naturopath will help better than I know how, but this is sort of an overview of what you will need to think about.
One thing you will do is to keep a food diary, but that's just the begining. I would start now, so you'll be more ready when you have your first appointment.