Please visit to a good Physiotherapist for Assesment so he or she can plan treatment accordingly. As far I understood there may be chances of mechanical backpain (Postural problem)...
Next Steps
Use Hot fomentation for 15min along with Dynapar gel twice in a day.
Do exercises flexibility of spine & hip as well specially while getting up from bed like Knee to chest,Pelvic rotation, can n camel & child pose.
Use firm mattress neither soft nor hard while sleeping or lying down.
Use backrest/cushion while working or sitting on chair. Avoid without support sitting.
Health Tips
Avoid/Stop exercise which aggravate pain ( I am not talking stretching pain;Stretching pain is normal experience).