If your stomach is uncomfortable when you are sitting or lying down, it may be caused by gastric disease or abdominal inflammation, such as gastritis, gastric ulcer, appendicitis, etc. The pressure in your stomach increases when you are sitting and decreases when you are standing or lying down. When sitting, the pressure in the stomach increases, and when standing and lying down, the pressure in the stomach decreases, so there can be the phenomenon of discomfort in the stomach when sitting, and when standing and lying down the stomach is fine, this kind of phenomenon may be caused by gastric diseases, such as gastritis, gastric ulcer and other diseases, you can take omeprazole, bismuth potassium citrate for treatment, the drug needs to be applied under the advice of a doctor. Before using the medication, you need to go to the hospital for further judgment through gastroscopy, if you exclude gastritis, gastric ulcer and other diseases, you need to consider whether it is caused by inflammation in the abdominal cavity, such as appendicitis, cholecystitis and other diseases, you need to be further judged by abdominal CT.