At your age, improper posture and prolonged sitting can cause such issues. If you are not careful, you may develop 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 (1 tablet before breakfast in the morning for 7 days)
*Do Bhujangasana (start with 5 counts...and then slowly increase the number of counts till you reach 40 counts per day). This is very important!
*Avoid sitting on a stool/chair for more than 15 minutes at a stretch. After every 15 minutes, get up for 1 minute and then sit back again. This is extremely important!
*Whenever you sit on a stool/chair, sit ahead on its edge. This way you will automatically sit straight. If you sit back and try to get back support, after some time, you will bend backward...this will worsen your spine problems.
*Avoid riding bike/car as much as possible
*Avoid sitting on soft sofas
*Avoid bending forward with your knees straight. Bend your knees and then bend forward.
Next Steps
Follow the above steps and let me know if you have pain relief after 1 week.