Cramping 5 days prior to ovulation. Any ideas?

I have regular 25 day cycles and usually ovulate 14 days before my period. Right now I am five days away from ovulation. However, I have dull cramping/twinge of pain that began on my right side. My OTK (ovulation test kit) did not detect a surge in my LH this morning or afternoon so I know I am not about to ovulate. Does anyone else ever experience this? I often times get ovulation pain (mittelschmerz), but I usually feel it around the time I am supposed to ovulate. Does anyone ever get cramps this early before ovulation? Any ideas what it may be if my OTK says I am not about to ovulate?