Pressure/fullness in abdomen

This month I never got my Positive opk and glow said my peak day was almost a week sooner than normal. However the last three days I've had this weird pressure/ fullness feeling in my lower abdomen. If I push out my stomach, stretch, or push on it it feels weird. It's not painful. What could it be? I'm scared it may be a cyst or some other problem. Anybody have any experience similar?