Sounds like me when I ovulate. For me, it's an internal hip pain of sorts, that starts out feeling like pressure and makes me think I'm constipated. Took charting to make me realize what the hell it was...after years and years of being confused!
At times it has been so bad that every step I took I could feel the pain being 'jarred' and it hurt! Those bad times the pain would last a couple of days.
Best way to be sure is to chart for a couple of cycles.