It's because of muscle weakness of the back either die to overuse /lack of use. You should consult a physiotherapist to get proper strength /balance to get rid of pain.
Next Steps
Go to a physiotherapist.. Heating therapy +some strengthening as well as stretching exercises will be helpful for sure. l
Health Tips
At home.. Rest +hot water fomentation +pain killer gel +no long sitting /standing /travelling /driving +no cold exposure +no manual exertions +no weight lifting.