<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have been having a lot of pain and swelling in my knees lately. What could be causing this?  <response>: Based on your symptoms, it is possible that you have osteoarthritis in your knees. This is a type of arthritis where the cartilage in your joints wears down over time, causing pain, swelling, and stiffness. 