When you sit down, your stomach is uncomfortable, usually due to various diseases that cause abdominal distension. Because of the bloating itself, the abdomen is compressed when sitting down, which leads to further relative aggravation of the bloating and leads to discomfort. If the upper abdomen is distressed and accompanied by bloating, belching or even stomach pain, it may be due to acute or chronic gastritis, gastric ulcer or duodenal ulcer. If this occurs in the middle abdomen, lower abdomen or even the whole abdomen, it may be due to gastrointestinal tract dysfunction, or even serious intestinal obstruction and extreme swelling of the abdomen, and also in patients with cirrhotic ascites.