The cause of your pain could be many ranging from inflammation of the pre- patellar bursa to a problem in the knee joint itself which you are mistakenly assuming to be below the joint. An orthopaedic pathology, especially when not very obvious from the outside, cannot be diagnosed without being properly examined and doing certain prescribed physical stress tests by the doctor on the involved joint. But for starters, try and feel the joint and try to appreciate any tenderness on pressing with the finger. If there is any pathology in the menisci, or other ligaments around the joint, you will feel pain at certain points. Bursitis is a possibility but the recurrence cannot be explained unless you have been engaged in a physical activity such as kneeling down.
A damaged knee joint is prone to undergo quicker degeneration than usual. A join that has withstood injury and surgery obviously does not have the same structure as a normal joint and so cartilage wear and tear is more common and quicker. This is the cause of early onset osteoarthritis of the knee which could also manifest in similar ways.
I suggest that you contact your orthopedician as soon as possible. He will probably ask for an X- ray to be taken to visualize the joint properly and identify any osteoarthritis. Ligament and menisci problems can be identified by doing specific maneuvers on the joint and interpreting the results accordingly. But for the pain, you may continue taking ibuprofen. Heat or cold compresses can be used too. This also relieves pain to a considerable degree.
Kindly rate this answer and please ask other medical questions or concerns you may have.
Refer www.askmdx.com to your friends and family.
Like us on Facebook http://www.facebook.com/AskMDx