Any info would be great, because the back of my right knee hurts and I was just wondering because I keep messing with it and poking it. Maybe that could be why it hurts,

Uh, I really don't know. I always have knee issues right before I start my period though. I didn't used to when I was younger, but I guess now that i'm older I get more fluid build up in my left knee and it hurts like crazy till after I start. Or maybe you just upset it by sleping in a funny position, or turning too sharply? I don't know much about lymph nodes though.

If you are ever in doubt about something like this, you should talk to your nurse at the dr's office or go see the dr as it will help ease your mind.
Good luck!

Ha, yeah that's probably the better advice. :d