Hi, There are several possible explanations for diarrhea after a lower back injury. One possibility is that the fall and subsequent injury could have triggered a stress response in your body, which could lead to changes in digestion and bowel movements. Another possibility is that the injury itself could have led to inflammation in your gut or other parts of your digestive system, which could cause diarrhea. Additionally, if you have been taking pain medication for your back injury, this could also be a potential cause of diarrhea as it is a common side effect of some pain medications. It is important to keep in mind that diarrhea can also be a sign of more serious health problems, such as infections or other medical conditions. If your symptoms persist or worsen, it is recommended that you seek medical attention from a healthcare provider. They can assess your symptoms and determine the underlying cause of your diarrhea, as well as provide appropriate treatment if needed. In terms of your back pain, it is important to seek medical attention if your pain is severe or worsening, as this could be a sign of a more serious injury. Your healthcare provider may recommend imaging studies, such as an X-ray or MRI, to assess the extent of your injury and determine the best course of treatment. In the meantime, rest and gentle stretching may help alleviate some of your discomforts. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Priyanka, General & Family Physician