Its postural backache. It generally occurs because of muscle weakness. Cause of the weakness is overuse of back muscle in prolonged sitting /travelling /standing.
Next Steps
Go to a physiotherapist.. Ultrasonic therapy +IFT +Heating therapy +some strengthening exercises and stretching exercises will be helpful.
Health Tips
At home.. Rest +hot water fomentation +pain killer gel +no long sitting /standing /walking /stair /travelling +no cold exposure +no manual exertions+no weight lifting +sit tall.