The crackling sound that you hear when moving your neck could be due to stiffness of the neck muscles. Muscle stiffness of vertebral muscles (including the cervical, or neck muscles) can be caused by reflex muscle spasms that occur during cases of cervical spondylosis. Spondylotic changes (osteophytes and disk hernias) can create pressure on the spinal nerves causing itching, numbness, pain, muscle pareses, and paralyses. Pain experienced during spondylosis has possibly double origins. The pain can be neural or muscular pain. Neural pain is due to the pressure on a sensitive spinal nerve and is found in the places that are innervated by the affected nerve. Muscle pain is due to a muscle spasm (prolonged contraction) of the vertebral muscles. Pins and needles in the hands and feet can also be due to the spondylosis. Headaches could be caused by muscle spasms. An X-ray of the whole spine is the proper protocol for confirming or excluding spondylosis. You can consult a neurologist or an orthopedist to inquire about the procedures and to further discuss neck problems.
Eye, ear, bladder and bowel problems are probably not connected with a possible case of spondylosis. You can seek assistance with the proper specialists: an ophthalmologist, an ENT specialist, a urologist, and an internist respectively.