Ovulation tummy pain is not the best way to tell when ovulation is occurring, because during ovulation the follicles rupture causing some irritation to the uterus and pelvis, thus producing abdominal pain. The pain will occur during or after ovulation, not before, so it is not possible to tell exactly when ovulation is occurring. You can only tell when ovulation is occurring at a certain stage, but not at a specific time. If you want to determine when you are ovulating, you can go to the hospital for an ovulation test. You can observe the development of the follicles through ultrasound, and when the follicles reach a certain level of development, they will rupture and expel the eggs. The abdominal pain that occurs during ovulation is a normal physiological manifestation and does not need to be treated, so you can rest more during the day.