Resurface of an old injury

Yesterday I was doing some new stretching at PT that I never done or seen before, much more contorting than normal.  During the end of the stretching I felt instant pain (3/10), I immediately stopped and straightened up.  For the rest of the day I felt the pain for the majority of the day, especially when I sat down.  I thought the pain was related to a bruised tailbone a few years back, but when I actually compared the location of the pain on my back i was suprised.  I found that it wasn't located in my tailbone , but my lumbar region of the spinal cord...I’m thinking of requesting an MRI for that area, especially since there has never been an image taken before.  This isn't the first time i've had issues in that area, but so infrequent that when i was at an appt i never remebered to bring it up with the doc.
For now i'll hope for the best and it won't be a pinched nerve or some "new" problem