Hello, I am Dr. Agniva Ghosh Dastidar, practising Orthopaedic surgeon. The problem you're referring to is very common in your age group. Some other information will be helpful to reach a diagnosis. Does the stiffness increase after getting up from a lying down posture? Does it increase during winter period? Do you have history of lifting heavy weight? Is there history or Arthritis in your family
Next Steps
Get a Digital xray done for lumbo-sacral spine in AP and lateral view. Start spinal stretching exercises. https://youtu.be/n6Etl3x9AnU?si=xnEs1ffsVH0gv0jF You can try the exercises in this link or search for other ones in YouTube.
Health Tips
Strictly avoid forward bending in a standing posture, lifting heavy weight and sitting on floor or squatting