I believe if the pain is regular, usually it's a case of muscle weakness or improper lifestyle. In rare cases it's other things. For better understanding, consult a good physiotherapist nearby you.
Next Steps
Apply hot fomentation, rub your back with some pain killer gel, and do strengthening exercises of your back. Stretching must.
Health Tips
Drink plenty of water, milk, eat fibre rich food, have food rich in
vitamin c, avoid long sitting, forward bending with straight knees.