Back pain need descriptive examination, consult a physiotherapist for better understanding

Posture corrections must. Stretching and strength exercises of spine

Postural Correction- Sit Tall, Walk Tall, Stand Tall.

Exercise to Get Rid of Your Low Back Pain! - by Dr.Pooja Pandey Tripathi(PT) https://www.practo.com/healthfeed/exercise-to-get-rid-of-your-low-back-pain-32455/post Read this article.

Hi You have to get your back assessment properly. If the pain is all through spine need to be assessed first.

Cannot get your question since how many days the pain is there 

Your pain could be of end number of reason Secondly Just get done your Back examination from physiotherapist and rule it out the the reason of your pain .

It may be cause of posture & may be also you are experiencing stiffness in spine especially in morning while getting up from bed. Well,If I consider you are not having any spinal deformity like scoliosis or flat back then you should go for Hot fomentation for 15min twice in a day also do knee to chest exercises, cat & camel, child pose & pelvic bridging. Better way you can visit any physiotherapist nearby. Also you should go for vit.d3 fasting blood test. If there is deficiency of vit.then can go for either injection(in case of severe low) or multivit d3 medication.

You need to get an XRay to be sure. Do you have a desk job? Did you hurt yourself? Lift something heavy? You need to meet a physiotherapist who can do complete postural analysis. It’s difficult to give information based on little information provided.