How is Neck Pain Diagnosed?

Initial examinations

Generally, neck pain is diagnosed by a medical history and physical examination. In other words, when you visit your doctor, firstly he will ask you some questions about your medical history such as symptoms, injuries or illnesses, any previous treatment, and habits and activities that may cause your neck pain, and next he will do a physical exam. Through the physical exam, your doctor can check your neck motion range and can know whether your pain is cause by improper movements. He will also look for tenderness areas and any nerve-connected changes, such as numbness, tingling, or weakness in the arm or hand.
In most cases, blood tests are only be done for an illness or infection.

Source: http://www.neckpains.org/how-is-the-neck-pain-diagnosed.html

However, if after above examinations, there are no signs of your medical history or recent injury, or adversely, after a period of treatment, your neck pain has not got any improvements, your doctors may suggest you to have some imaging tests, such as X-rays.
Imaging tests are available when

— Signs of nerve damage occur on you
— Another serious problem is suspected by your doctorHow is the Neck Pain Diagnosed?
Neck Pain Symptoms and Signs
Surgery for Neck Pain Relief
Medications for Neck Pain Relief
Neck Pain Prevention and Relief
Physical Therapy for Neck Pain Treatment
Home Remedies for Neck Pain
Effective Neck Pain Treatment Options
Causes of Neck Pain