<<Disclaimer:  Verify this information before applying it to your situation.>>
 
Not mediacl advice
 
There are many possible connections between nack pain and CD
The most likely problem relates to osteoporosis and shortening of the
spinal,column. Another possibility is the weakenin of the back muscles
due to malnutrition and loss of muscle mass or calcium and magnesium
deficiency leading to weakness.  each of these can lead to poor posture
which further leds to pain.  Osteomalacia ( due to Vit D def is a
specific type of bone problem that leads to weak bones.
 
Another cause of back pain is referred pain from the small intestine to
the back.
 
These are just some of the causes of back pain in asociation with CD
 
Joe Murray