as you have excruciating pain in neck and back of head, and you are diagnosed cervical spondylosis
along with you are having facial neuritis most probably.Therefore I like to advice you to go for cervical spondylosis by having physiotherapy
treatment ( Neck traction treatment ) regularly and neuritis treatment by consulting neuro physician for treatment of possibly facial nerve infection
or involvement as you described your symptoms.Till you consult your neurologist
you may take some nerve supplements such as vitamin B1 B6 B12 and analgesics to relieve your symptoms.
Hope you will be satisfied by my advice and will take necessary steps to get relive from your symptoms.take care, good luck.