Degenerative disc disease can cause numbness. And, since you have a tender spot on your back, I would guess you have some inflammation as well which can effect the nerves. I think an MRI is a good thing. Are they doing the whole spine, cervical, thoracic, or lumbar or even a combination of any of these? Are they doing it with and without contrast?

Check out this link and see if any of the symptoms and descriptions fit your situation.

http://www.webmd.com/back-pain/tc/de...verview?page=2

I hope you start feeling better soon and find some answers as to what is causing your symptoms. Let us know what happens and if we can answer any questions.