At this age generally wrong sitting and sleeping pattern may be the reason for back ache, untill you show any history of Trauma to veribrae.
Next Steps
Having panchakarma ie Abhyanga swedan and Kati basti will heal you soon
Do have Xray of Lumber region and check Vit D3 level Vit
B12 And Serun Ca level to rule out if any?
Health Tips
have Yoga and walk may be with lunber belt