Hi. Noted your history of belching on exercising, even on taking deep breathing, otherwise you are an exerciser most of life. All your history is suggestive of a condition called GERD that is gastroesophageal reflux disease. This can be diagnosed by the following ways: Upper GI Endoscopy after consulting a Gastroenterologist, Barium swallow. In most of hte cases the diagnosis will be done and thus an appropriate management can be added on. Simethicone alone can not help. You may be prescribed additional PPI like Omeprazole or so. Domperidone as motility regulator. Diet adjustment by avoid the foods and beverages along with other factors like stress, anxiety should be avoided. Avoid oily and spicy foods. Have proper sleep and relaxation. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. T. Chandrakant, ENT & General Surgeon