<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have been experiencing leg pain, fatigue, muscle weakness and leg weakness for a while now. What could be the problem?  <response>: Based on your symptoms, it is possible that you have Amyotrophic lateral sclerosis ALS. This is a progressive neurological disease that affects nerve cells in the brain and spinal cord resulting in muscle weakness, including weakness in leg muscles. 