ewww... Soccer chick those are some pretty grosse lookin pics... You could have done more than one thing there, you definately could have damaged some ligaments from the extension and also damaged something on impact. I showed the picture to my Dad and he said.. Medial Colateral Ligament Sprain.
But he's just guessing, he was a Human Physiology Masters student in University.
Make sure you are keeping the knee elevated and LOT's and LOT's of ICE!!!! Compression wouldn't hurt either, with an Ace or Tensor bandage.
Bruises could definately be caused by impact but also if something tears, a Bruise is bleeding so it's not the best sign.
Give it a couple of days with REst, Ice, Compression and Elevation ( Elevation means above the level of hte heart) and i'd probably get in to see your doctor.