Hey,
There could be many reasons for your problem, it may be because of abnormal posture, your gait(how you walk), your footwears, your sitting posture, your daily habbits which may be causing change in your spine curve, nerve impingement etc, you should consult with a good physiotherapist near you before starting any exercise
Next Steps
Change you poor habbits if you know any and consult with a physiotherapist he/she will help you better after diagnosing your problem's cause
Health Tips
Go for a regular Physiotherapy treatment for a better results and prolonged relief