Thank you for your question. Although without being able to examine you I can not offer you the specific advice on diagnosis and treatment that you need, but I would try to provide you some relevant information about your health concern.
This can be due to Cervical spondylosis, muscle spasm or due to nerve irritation in the cervical (neck) spine because of injury/prolapse where contact between the edges of the vertebrae can cause neck pain. In few people, this pain may be referred and perceived as occurring in the back of head, shoulders, arms or chest, rather than just the neck. Main 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/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.
Have you sought medical attention?
Do you have high blood pressure or a heart condition? Any health problems?
Being that you have been under alot of stress it could just be anxiety induced.
Please seek medical to rule out anything serious.
Keep us posted.