Why do I have a "swollen" feeling on my lower right side?

I feel like I'm ovulating because I have a thick, clear mucus that is ociated with ovulation (I know -graphic and gross-sorry!) but I am supposed to be starting my period around this time but my aren't swollen or tender yet (and that always happens). I am having a weird pain (only when I move a certain way or lie a certain way) almost as though something in my lower right side is "swollen" but it doesn't appear swollen. I am wondering if this is just one of my ovaries or if I should be concerned. Thanks for any help!