Wow, that sounds like quite a fall. 18 stories almost always results in death, but it sounds like you got away with minimal injury. I would say that if your low back pain and numbness in the feet were specifically due to the fall, you would've experience this immediately afterwards. However, they should be worked up in the same way. Low back pain radiating down the legs is called lumbar radiculopathy and I recommend seeing your primary care physician
. The first thing to do to work out this problem is for you to have an MRI of lumbar spine. This will show if there is a herniated disc, spinal stenosis, or some other reason for you to have radiating pain down the legs. Depending on the results, your primary care physician will choose to refer you to either a neurosurgeon
or a physiatrist
. A physiatrist will developed a plan to treat your pain with physical therapy and specific injections to relieve areas we have pinched nerves. A neurosurgeon will be better at determining if surgical solution exists to relieve your pain. If the MRI is normal, then you might benefit from a work up for lower extremity vascular disease which in some cases can present in this way. For starters, I would schedule an appointment with her primary care physician for further assessment so that it is more clear what diagnostic testing needs to be done.