Hi, As you have Spondylitis I would recommend you to take an MRI of the cervical spine so we understand what are the soft tissue changes happening in the cervical spine. We need to check what are the disk getting trouble due to degenerative changes in the cervical spine. on and off neck stiffness is due to any compression happening with the spinal nerve root or maybe the spinal cord by the intervertebral disc. Due to this there might be you and stiffness or maybe inflammation of the trapezius muscle so I would advise you to first start using the neck collar we should be a soft neck collar. post applied the soft neck collar maximum number of times or minutes or hours a day I would like to advise you to take hot water fomentation to the neck and upper back. As the pain symptoms comes down I will advise you to start doing mech static strengthening exercises which may help to avoid applying pressure of the intervertebral disc to the spinal nerve root or the spinal cord by which you can avoid the frequent neck stiffness. In my clinical practice of over 12 years I have always seen people complaining of the neck stiffness and heaviness in the head this happens at the craniovertebral junction so we recommend them to take an MRI and come back so we find there are changes in the cervical spine and the intervertebral disc causing compression and changes. most cases recover with soft collar hot water fermentation and neck exercises. Hope I have answered your query. Let me know if I can assist you further. Regards, Jay Indravadan Patel, Physical Therapist or Physiotherapist