I have similar neck problems and have had good success with a nerve root block for pain. They are kind of tricky and I would only have it done at a center where they use X-Ray to hit the right spot because if they miss it's pretty much a waste of money and not a comfortable procedure either. I previously had a ruptured disc at C5-C6 and had a fusion and was able to continue biking for two years. However, continuing disk degeneration and cervical stenosis had pretty much made it impossible to ride last year. I had six months of relief from a nerve root block. I would think with the condition of your neck, you doctor would frown on your being on a MTB. Have you thought of turning things down a notch and going for a road bike before you are unable to ride at all? I didn't listen to the warnings they gave me, thought I was invincible, and am now paying the piper. BTW, the road bike I ride is more upright which also takes stress off my neck. Hope this helps. Just trying to tell you to listen to what your body is trying to tell you.