Most probable reason of lower back pain is spine disc herniation. Especially if the pain radiates to the leg and travels through buttock...other reasons being degenerative diseases,muscle issues etc...For spine diagnostics, MRI is necessary...Ensure that you maintain an appropriate posture while working or sitting or walking....Take frequent stretch breaks and drink lots of water...Discontinue using pillow while sleeping straight...Do not lift heavy objects, especially after bending down....Consult nearest orthopedic surgeon they will do the needful.