If this is something new that Sandy is doing, I'd be a bit concerned too. Have you changed the food or anything else in the regimen? If not, you might try adding some probiotics to the food. You can buy them at most pet stores or online.
Otherwise, it might be a reaction to the food or, as others have said, eating or drinking too fast. Mine usually burp after eating, but not in between unless they've been drinking water. If your dog is a fast eater, you might try slowing him down with one of the bowls designed for that.
Or, since he's 7, raise his food bowl off the floor. I always raise the bowls of my older dogs to keep them more comfortable. You can just use a thick book or two or even a box to put the bowl on, or there are dog dish holders you can buy.