Hi...
If it's on the sides then it could be Sciatica pain.
If pain is on spine, then could be spondylitis..
Next Steps
Go for AYURVEDA panchkarma therapy, like Kati basti and Potli.. it will give instant relief.
take mild laxative like triphala for releasing pressure.
or apply hot ayurvedic oil at affected area, then give hot fomentation.
Health Tips
take care of your digestion , and relax your mind.