Thank you for your query at DoctorSpring.com.
The feeling that you are somebody else and not you can occur in dissociative personality disorder which is a psychiatric illness. If this feeling persists, you should consult a Psychiatrist.
I have gone through the X-Ray of your neck. It shows cervical spondylosis. This can lead to neck pain, and pain at the back of the head as well as upper backache.
For the pain, you can take OTC Ibuprofen 400 mg, twice a day for 3 days. You should also do neck exercises to reduce pain in the long term. You can consult a physiotherapist for the exercises as well as for other pain relief measures.
I hope this was helpful.
Please let me know if you have any other queries.