A 70-year-old otherwise healthy female patient presents to the ER with cramping abdominal pain and vomiting for the last 6 hrs. Abdomen is distended with diffuse tenderness all over and exaggerated bowel sounds. Abdomen is virgin and hernia sites are intact. In Pelvic exam, a tender mass is felt on the left side and Howship-Romberg sign is positive. What is the most likely diagnosis?