If you have posted truthfully, the liklihood is that you have what is called a subluxion injury, commonly known as "whiplash". The injury is common whenever the neck is quickly flexed. It is indeed due to compression of the nerves in the cervical area. It is definitely not cardiac-related. Sometimes these get better and sometimes they become progressively worse, often months or years after the initial injury, leading to what is called a "frozen shoulder" paralysis of the hand and chronic pain. Often the poeople who complain are called hypocondriacs and referred to psychiatrists. A cervical collar is contraindicated. It will decrease muscle tone. Muscle relaxants are also contraindicated. Treatment generally involves good hydation, intermittant daily axial traction for weeks or months and anti-inflamatories, then "range of motion" exercises. Years ago prednisone for several days was the initial treatment of choice, followed by ibuprufin. These injuries will not show on an x-ray. An EMG while symptoms are being experienced will evidence a degraded signal. It is difficult to find a physician familiar with these injuries that knows how to treat them.
Thank you very very much for your detailed response. He is a bit of a hypochondriac, but tingles down your arm can be a bit scary. He says that this neck problem happens whenever his heart races, so I thought I'd ask. Thanks.