Gas, bloating, and belching are associated with a variety of conditions but are most commonly caused by functional gastrointestinal disorders. These disorders are characterized by disordered motility and visceral hypersensitivity that are often worsened by psychological distress.
Roma IV
Rome IV Diagnostic Criteria for Nausea and Vomiting Disorders
Nausea is a subjective symptom and can be defined as an unpleasant sensation of the imminent need to vomit, typically experienced in the epigastrium or throat. Vomiting refers to the forceful oral expulsion of gastrointestinal contents associated with contraction of the abdominal and chest wall muscles.