Hello~I would stop the carbonated drinks, and take a good, high potency pro-biotic to put friendly bacteria in your gut. If it continues, see your physician.
Stop drinking carbonated beverages -- they're awful for you and they do make you belch. Look, I know this is hard for someone at your age to get, but peer pressure is intense at that age. But people are different. I learned to belch early because I had an older brother who taught me, but that's belching on purpose. Spontaneous belching because of what you eat or how fast you eat it sounds like what it sounds like.