There are many reasons for back pain, it can be because of structural changes eg Scoliosis, Sciatica or because of accidents , trauma or mechanical reason like long term sitting, wrong positions of working. Basically weaker muscles make you feel more pain so we must focus on strengthening of muscles.
Asanas by which we can reduce back pain are :
Sethu Bandhasan or Bridge Pose
Child Pose or Balasan
Cat and Camel Pose
Pavanmuktasan
Side Lumbar Stretch
Bhujangasan or Cobra Pose
Regards,
Dr.Aarti
http://sattvayogaalay.com/