It seems you are suffering from gastro-esophageal reflux disease, which is one of the commonest causes of belching
. Exercise worsens it by increasing intra-abdominal pressure. Try exercise at least 3-4 hours after food. Smoking
also worsens it. You were right to see a gastro-enterologist as some conditions like hiatus hernia
, peptic ulcer
etc need to be ruled out. If his treatment has not benefitted you, ask for a change in prescription. Also try to avoid ingesting air while eating/exercising.