I Struck A Doorway Corner With My Right Knee About

I struck a doorway corner with my right knee about a month ago. A few days later, I felt a pop in the same knee while trotting to my car in a store parking lot. No pain, just a sudden feeling of something giving. The knee has been swollen for most of the time since around then. I have a residual tightness in my lower quad and upper calf muscles of the right leg. It is not uncomfortable to walk, but the persistent swelling on the outside of the knee cap concerns me that I must have some injury that is either not healing or is very slow to heal. Got any suggestions?