First, how did the original pain start? If you’re not sure then what had changed in your routine in the weeks leading up to the pain? I ask this because it may give a clue as to what the problem is. 

It is a good idea for you to get an MRI. Arthritis may be triggering muscle spasm but there are a number of other possibilities, My philosophy is to have a good look at the structure especially to see what is going on with the discs. Go back to your MD and ask about getting an MRI.

You should also go see a good therapist (physio, athletic therapist, chiropractor etc…). Get a referral from friends and request a free consultation to discuss how they can help before committing.

There is definitely a bunch of therapeutic techniques that can help with pain and possibly to fix the issue.