Sour stomach is a group of symptoms (mostly related to stomach) that any individuals can experience and feel general uneasiness. Sour stomach also termed as upset stomach, acid re-flux, stomach bloating, stomach pain, excessive belching etc. Ideally speaking sour stomach is nothing but deranged health of upper gastrointestinal track which causes nausea, burning in stomach, belching, sour burps, indigestion and upper abdominal pain. This group of symptoms is termed as sour stomach.