Dear patient Your symptoms are suggestive of nerve root compression with disc prolapse as a reason of sudden her to your back. Sudden jerk while getting up from standing position may lead to disc herniation which leads to nerve compression and hence radiating pain in Lower limb. This needs to be investigated with 1. Xray of lumbosacral spine anteroposterior and lateral 2. MRI of lumbosacral spine to confirm diagnosis. Visit radiology center nearby you and get it done. Meanwhile take strict bed rest ant start tab Myospas forte twice a day along with tab pantocid 40mg twice a day for pain relief. Avoid forward bending and weight lifting. You need to consult expert spine surgeon with report. All the best.