welcome to Health care magic.
1.If you are my patient, i would have start with general examination.
2.Then a 
lumbar spine x-ray AP/LAT views, then depending on the findings i will go for 
MRI.
3.X-ry helps in the bony changes ( 
fractures,Lysis,listhesis ) and MRI help in Disc pathology, 
nerve related, chord.  
4.You can try as a remedy - do 
back pain exercises with positional maintenance and sleep on flat bed, there should be a lot difference.
5.If it not work, then take an appoint meant and get needful things done as mentioned.
Hope it helps you. Wish you a good health.
Anything to ask ? do not hesitate. Thank you.