Knee injury? Help as to what it might be?

I have been working out at the gym but last Thursday I walked home and as soon as I got home, my knee began to hurt. I couldn't walk on it for about a day or two and couldn't bear weight on it. It's gotten slightly better but now I have numbness all the way to my foot like it falls asleep and tingling, plus periodic twitching. I've got pain on the inside of my knee just to the side of my knee cap. Now I can walk on it for about ten minutes before I need to sit down again. Any idea as to what it might be?