Thanks for the responses! It does appear slightly swollen, but I may be imagining that. Now that I think about it, I did slightly injure my knee about five years ago while laying some sod in my yard. Every once in a while it would hurt walking down stairs, and really bad, to the point that I could not even bend the the leg to walk down the stairs at all. But once I really started getting into really good shape, that problem completely disappeared.(maybe from strengthening the muscles?) I will take your advice and give it a week and answer all of the questions that you have listed in case I need to see a doctor.
Thank you for your help, it is nice to find people that are willing to help you out of the goodness of their hearts! I will update you in a week!