Nothing showed on MRI or X rays?
Soft tissue - any PT sessions to see if "hands on" work can figure it out?
Expert chiropractic?
If only in bed? maybe mattress issue ?
many of the memory foam/gel mattresses are nice or a 3" or thicker mem /gel topper

Many have had results with the inversion products - decompresses any spine pinch points..
Inversion Tables | Amazon.com