A 50-year-old woman complains of acute pain in the epigastric region, vomiting, and sudden general weakness. The disease onset was 2 days ago. Objectively, she has pale skin and dry tongue. Pulse 100/min., of poor volume, blood pressure 110/70 mm Hg. During palpation, the abdomen is soft, moderately painful in the epigastrium and mesogastrium, there are no signs of peritoneal irritation. Peristalsis is significantly increased in the mesogastrium on the left. X-ray detected Kloiber bowls (air-fluid levels) on the left. What is the most likely diagnosis in this case?