Generally classic whiplash occurs after suffering a car accident. At the time of the shock or the brakes, the seat belt holds the body but not the head. This and the neck is suddenly moving forward and back as if it were a whip, hence the name. The muscles and ligaments of the neck, because the driving force, are stressed with such violence that have just suffered an injury. The initial pain and stress seem to disappear after a few days or weeks, but may return after a short period of time.
Other triggers are typical of a high impact lash, blow or jolt, when playing sports, etc.

in this situation, the presenting symptoms are:

Pain and stiffness in the neck and / or shoulder during the first weeks immediately after the impact. Then it seems that you feel better but the pain and stiffness are again a few days later.
Pain is not unbearable but uncomfortable in the lower back.
Pain in arms and / or hands or feeling of falling asleep.
Visibility blurred.
Dizziness.
Difficulty concentrating.
Ringing in the ears.
Tiredness and irritability.
Insomnia.

Given these symptoms, what can you do?

It is advisable to consult a doctor to determine the severity of the injury. Probably advise you take medication or make you wear a collar to prevent strain on neck muscles. It is normal to be prescribed as soon as possible a series of special exercises to strengthen muscles.
To combat the pain, help you take painkillers. During the first 24 hours, the cold reduces swelling and pain in the case there. It is best to lie in bed and under the neck put an ice pack wrapped in a towel for 20 minutes, making small pauses.
During the first weeks you should not make sudden movements or efforts, such as lifting or carrying heavy things, or play sports that involve strength.
When the neck has recovered, you should practice specific stretching techniques to prevent pain and stiffness.

It is very important to seek medical attention to the following situations:

When you after impact caused initial pain from coming back pain and neck stiffness.
If the pain spreads to the shoulders or arms.
If you notice some discomfort in the arms, or tingling sensations as they fall asleep.
If your head hurts to move it.
If you experience nausea, vomiting or difficulty swallowing notes.
If there are problems of concentration, vision, or insomnia.

In short, do not resign yourself to suffer this pain in the neck that seems to have settled forever. The advice of your doctor and some tricks and exercises can help.