it seems like a muscle strain probably due to ongoing muscle weakness.
it can progress to disc compression if proper tratment is not taken.
Next Steps
Consult a Physiotherapist
*Ice pack *Ultrasonic waves *Laser *Tens *Massage
Followed by strengthening of back muscles
Health Tips
Use ice pack 3 times a day for 10 minutes.
Avoid bending of back instead fold kness to pick up things from the floor.
No lifting of heavy weights.
Try using a backrest while sitting for long hours.