Answer
Athletes commonly injure their knee joints.
Possible specific lesions: Tears of the anterior cruciate ligament and of the medial meniscus.
Swelling secondary to damaged blood vessels and torn synovial membrane (and torn meniscus).
Work Step by Step
Continued swelling is probably due to accumulation of synovial fluid; this would cause pressure, pain and immobility,
Jeremiah's doctor would most likely aspirate the extracellular fluid ( drain the water off the knee), and would consider an arthroscopic exam to check the extent of the knee injury.
