can't bend

[flygirl]

Hi all, I was just wondering if there was anyway someone could please tell me or give me an idea as to maybe what I have done to my knee. I was just sitting on my friends porch step, and when I went to get up, I had some pretty good pain on the upper/outside of my knee. It really is painful to bend it all the way say like when I am going down the stairs or try to cross my legs, also just when sitting in a chair....HELP what have I done? I know someone is going to ask if I have had a blow to it no, I did spend about 3 hours on my knees 4 days ago scrubbing floors...other than that nothing to strain it that I know of...

BTW thanks in advance for any and all help!