Please check your Vitamin D3 and B12 levels and let us know. Weight reduction if you are over weight.
Posture control as suggested. X-ray of lumbar spine and sos MRI may help diagnosis. You need to see an Orthopedic specialist personally
Most probable reason of lower back pain is spine disc herniation. Especially if the pain radiates to the leg and travels through buttock...If you have also frequent urinating, burning while urinating, kidney infection can give back pain as well...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....Eat a healthy wholesome meal which should satisfy your minerals and proteins requirement...take over the counter pain medications.. Consult nearest orthopedic surgeon they will do the needful.