<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have a lump on my knee and its difficult for me to move my knee. I also experience spasms on my elbow, stiffness on my knee and shoulder pain. What could be the problem?  <response>: Based on your symptoms, it seems that you are suffering from Hemarthrosis. This is a condition where there is bleeding into the joints which can cause swelling, pain and limit your movement. 