<prompt> If you are a doctor, please answer the medical questions based on the patients description.Three months ago I fell while walking down stairs and landed on my back. No major pain at the time, just soreness. Now that area of my back is sore to the touch and sometimes tight, painful in the morning. It s the lower back, on the spine. I have no trouble with movement or lifting. Should I have an x ray? What are possible explanations?  <response>: Welcome to Chat Doctor. Thank you for posting your question. I can understand your concern. Low back pain can be due to a lot of reasons :1.muscle strain2.muscle spasm3.osteoarthritis4. Disc prolapse5.HLA-B27 associated arthritis including ankylosing spondylitis, reactive arthritis, psoriasis arthritis, and inflammatory bowel disease6.spondylolisthesisThats all about the information. Do not worry too much. I would suggest you to take combination Chat Doctor. 