Ovulation usually occurs two weeks before the first day of each menstrual period, give or take a couple of days. During this time, you may feel pain in the pelvis that can range from a sense of discomfort or a mild twinge to severe pain that mimics appendicitis. It usually lasts a short period of time, from a few minutes to hours. It often is felt in the lower abdomen or pelvis, either in the middle or on one side. If the pain is severe, it may be accompanied by some mild nausea.