<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have been having some unusual symptoms lately. My elbows feel weak and so do my lower back, and my knees are swollen. What could be the problem?  <response>: Based on your symptoms, it is possible that you may have Thalassemia. It is a genetic blood disorder that affects the production of hemoglobin in the body. This can lead to a deficiency of oxygen in the body causing weakness and swelling of joints. We need to run some tests to confirm the diagnosis. 