Regarding the cervical spondylosis, I would recommend a consultation with a neurologist to have this evaluated. If he has persistent symptoms despite chiropractic manipulation, this would suggest to me that the manipulation is not helping. If he has not had an MRI, it would be reasonable to do so. This will permit the neurologist to visibly see what structures are involved, and then make the appropriate treatment decision.
Regarding the other symptoms, I do not think they would be caused by the spondylosis. I am not an endocrinologist, but the symptoms are not all explained by hyperthyroidism. I would recommend that you see your primary doctor about this issue. Good luck.