What can be left lower abdominal pain and nausea in a 61 yr old man overweight and high blood pressure?

Many possibilities: Many different problems can cause left lower abdominal pain, some minor (irritable bowel), some serious (diverticulitis, kidney stones, colon cancer). In order to get to the bottom of this, a complete history must be taken, followed by a careful physical exam, lab tests, and other tests which may include x-rays and/or endoscopy. Please make an appointment to see your primary care doctor.