I don't know, does your shoulder-area hurt when you move it also or is it just when you burp?
Right shoulder-area pain can be referred pain from many different places - gallbladder, esophagus, stomach ulcer, pancreas. Since it's when you burp, I'd guess it has something to do with your esophagus, a spasm maybe. You should see your doctor for a check up, just to make sure it's nothing serious.