Cyclical pain, pain that's related to the menstrual cycle, in a reproductive age woman, almost always has something to do with hormones and ovulation. Any abdominal or pelvic pain occurring monthly should be examined to see what changes of anatomy and physiology may be responsible for causing the pain.
Many times the diagnosis of such pain is very difficult unless diagnostic studies are used or exploratory surgery such as laparoscopy is performed to look inside the abdomen. The exact timing of when and how long the pain occurs in relation to a monthly menstrual cycle can often be a clue as to what types of pathology to look for on the imaging studies or surgery.
What would cause pain occurring 7-10 days before menses each month?
In the week or two prior to menses a corpus luteum cystic gland forms on one of the ovaries at the site where an egg was released from that ovary. This is a hormonally functional gland that produces progesterone primarily. The gland causes the ovary to become larger and heavier for a while until the cystic area goes away when menses starts.
The other main pelvic change in the week or two prior to menses is that the veins of the pelvis often swell (dilate) under the influence of progesterone. They can become like varicose veins of the pelvis and sometimes will produce a throbbing pain, but which lasts throughout most of the last week of the cycle.
Since the pain only lasts for 3 days and it does not start 14 days before menses but rather 7-10 days, the best guess as to cause would be that the pain has to do with the enlarging ovary on the right. One would expect the pain to alternate sides if it were due to a corpus luteum gland because ovulation usually alters one month from one ovary and one month from the other. However we have seen ovulation occur pretty regularly from only one ovary even though there appears to be no disease in the other one.
Pain occurs when the enlarging ovary "pulls" on any adhesions of the ovary to the surrounding tissue or simply when it stretches the ovarian capsule fairly rapidly. Adhesions cannot be seen on ultrasound or any xrays but if you have your pelvic ultrasound during the 3 days you are having pain, One would expect to see a cystic area (small) on the right ovary if that is where you are having pain.