A pain medicine doctor explains how to differentiate between appendicitis and menstrual cramps, common conditions that can present with similar lower abdominal pain, nausea, and fatigue. Key distinctions include appendicitis pain typically starting near the belly button and moving to the lower right abdomen, worsening steadily rather than in waves, and becoming sharper with movement, coughing, or pressure. Appendicitis may also be accompanied by loss of appetite, vomiting, or fever, with pain potentially becoming severe and widespread if the appendix ruptures.