Knee Sprain?

I was screwing around at school about a week ago and ended up falling onto my right side on some hardwood flooring.

I felt that weird knee pain you get sometimes when you hit a certain spot just right, its hurts like hell but fades in about 2 minutes. Well, I also have some lingering pain in the knee even now.

I had no swelling(still don't) in the knee, but I do have soreness on the left side of my right knee when I fully extend the knee or tuck it close to my body(like you would if you landed backseat). I didn't hear any pop and I didn't feel anything tear, but I'm wondering why the pain is still kicking around. I'm assuming its just a sprain, so I've been taking it somewhat easy, but how long do things like this take to heal up generally, and could it be something else?