lower back pain can be because of many reasons. it can be postural or mechanical. if you are having consistent back pain try to be aware of your posture and daily routine and start exercising.
Next Steps
start with (if you have basic strength) pelvic roll, knee to chest and tummy tuck and buttuck sqeeze, simple exercsie just to start and will imrove your mobility of your back.
Health Tips
consult a physio for more exercise plan and a detailed assessment.