Thanks for query,
You have not mentioned your age.
If you are elderly then it is possible you might have degenerative changes in your spinal vartebrae giving risr to low back pain
Go for X ray
lumbo sacral region and find out that is there any compression of vertebrae or any osteophytes producing this problem.
Consult orthopedic and get examined.
Go for back extension exercise and physiotherapy
Take calcium,Vit A,D, and other B.complex medicines.
ok and bye.