Dear lybrate-user Lower back pain
is because of so many reasons Starting from simple postural problem to compression at nerve roots One of d most common one is L4-5 disc disease causing nerve compression For seeking a relevant advice you need to answer few questions, Has to undergo proper set of specific tests to rule out certain specific disorders.
Every case needs a detailed understanding through certain investigations and evaluations.
However rest/ hot fomentation and few days of muscle relaxants usually works well It would be great if you can share your MRI
report (if not public then can share in private)
The good news is - its always treatable if timely addressed Good luck.