Massage therapy is one of the best ways to relieve a stiff neck. If you're massaging your own neck, use this technique:  Warm up the back of your neck by rubbing up and down with your hands. With gentle pressure, use your fingertips to rub in a circular motion on your neck. Focus on the areas that are most stiff, but rub your entire neck for relief.  Repeat this motion up and down your neck for several minutes. A massage therapist will work with you to figure out where your body is holding tension. While your neck may be stiff, you may actually have tension in other parts of your back or shoulders that builds in your neck. Check with your health insurance to see if massage is covered by your health plan. Acupuncture is the Chinese treatment of pain and other ailments by penetrating various strategic points of the skin with tiny needles. Although some question acupuncture's effectiveness, many chronic neck-pain sufferers swear by this treatment. See an acupuncture therapist for a consultation and ask them specifically about treating neck stiffness or neck pain.

TL;DR in Vietnamese:
Mát-xa cổ. Đến gặp chuyên gia mát-xa trị liệu. Liệu pháp châm cứu.