Most women who can feel their ovulation describe the sensation of more of a discomfort than a pain. I can sometimes feel my ovulation, and though the feeling is far too weak to be really called "pain" (because it is easy to ignore), it is certainly uncomfortable. It is not unlike the bloating feeling many women get just before starting their period. I used to think that ovulation pain was simply feeling how an egg made its way down, it actually is more than that.
Although the pain is distinctively related to the ovary where an egg is being released at that time, it is said to be caused by a small amount of blood being released from the ovary at the time of ovulation. This small amount of blood is later reabsorbed by the body, and the amount that is released impacts the strength of your painful sensation.
Ovulation pain is not a medical problem, in and of itself, but reproductive conditions such as polycystic ovary syndrome (PCOS) do make it more likely that a woman will experience pain during ovulation. If you are having ovulation pain and are worried, it would be good to see your doctor to determine if the pain you experience has any underlying cause that needs to be treated.