At your age, improper posture and prolonged sitting can cause low backache. If you are not careful, you may land up with slipped disc! Try the following:
*Apply hot water bag (10 minutes twice a day)
*After applying hot water bag, apply Nobel Gel
*Tab Flexon (1 tablet after lunch and 1 tablet after dinner for 7 days) (if you are not allergic to it)
*Tab Pantakind (40mg) (1 tablet before breakfast in the morning for 7 days)
*Tab Gabaneuron (300mg) (1 tablet at 7pm in the evening for 10 days)
*Lie down in your belly, keep both your palms beside your shoulders on the bed, then push the bed wiu both your palms so that your upper body is lifted off the bed, then bring your upper body back down to the bed (Bhujangasana).
*Lie down on your back on a bed. Fold both your knees, then keep both your palms beside your waist on the bed. Then push the bed with your feet so that your waist is lifted up off the bed. Then bring the waist back down on the bed (Bridge Pose). Both the above exercises should be done 40 times daily.
*Avoid sitting for more than 15 minutes at a stretch. After 15 minutes, get up for 1 minute and then sit down again. This is very very important!
*Avoid slouching back. Sit on the edge of the stool or chair so that you automatically sit erect.
*Avoid bending forward with your knees straight. Fold your knees and then bend forward.
*Avoid sitting on soft sofas.
*Avoid riding bike/car as much as possible.
Next Steps
Try the above steps and let me know if you feel better after 1 week.