It sounds like he gave you a C-spine (neck) MRI, not a T-spine (mid-back) MRI. It is the T-spine that "houses" the part of the cord (Lumbar) that may have lesions causing this type of pain.

Lesions in the L-spine are not that common actually, so it is more likely related to muscles, gait, etc. causing this pain. If the stretching exercises are helping slightly, keep with them if you can as they will further strengthen and relax muscles the more you do them.

I get lazy on doing them sometimes, but always go back to them when things get difficult again. :D

Cherie