The pain and distension on the right side of the abdomen may be caused by the following conditions: 1. If the pain and distension occurs in the right upper abdomen, it may be caused by cholecystitis, hepatitis or pancreatitis. 2. If pain in the right lower abdomen occurs, it may be caused by stones in the lower ureter or acute appendicitis, some gynecological diseases such as ruptured ectopic pregnancy, ovarian cyst torsion or ovarian corpus luteum rupture.