I get this pain every time I am mid-way between periods (ovulation) then again when I am on. I have heard its something to do with oestrogen levels.
I have to take a step back from running when it peaks, it normally has one or two days where it feels bad then the next day is unbearable- I mean I can't even travel on a bus without being in pain! I have to not run on these days and instead things like cycling, eliptical machine or the stepper are somewhat easier. I concerntrate on my core and trying to keep my upper body stable so very little moves.
I have yet to find a form of medication which helps and have been advised by a gynocologist to go on the pill which I refused as I am fat enough already and feel low enough about that already! There are apparently things such as the pill you can take though if its any help.