Thank you for your question. It sounds that his symptoms may be due to nerve irritation in the cervical (neck) spine because of injury where contact between the edges of the vertebrae can cause symptoms. In few people, this pain may be referred and perceived as occurring in the back of head & shoulders (as electric sensation)- LHERMITTES SIGN, numbness, arms or chest, rather than just the neck. Other symptoms may include vertigo, nausea (dizziness) and stiffness can be intermittent. It will be best that you consult a neurologist who would like to prescribe Pain killers, steroid and muscle relaxants. Other treatments could be cervical orthosis such as a soft cervical collar or stiffer neck brace to restrict neck movement. In addition, cervical traction may also be suggested by the doctor, if condition is severe. Hope this helps.
I assume you are talking about your cervical spine. You don't have alot of time to get to a Dr. and your GP probably can't help you with this except putting you on the meds listed above. Get that on board and have a good trip!