Re: Knee Pain
There are fluid-filled sacs called bursas in front of and behind the kneecap. I would imagine that the fall irritated one of them.
Keep icing at least twice a day. Don't do anything too demanding on that knee, although light exercise that does not cause pain is good. If it gets worse again, or doesn't seem to be improving, see a doctor.
Oh, since this happened at work, you might want to tell your supervisor and get it documented, just in case you do require medical attention at some point.