Whiplash injury is actually another name for neck strain. The sudden force that causes jerking of head forward or backward can lead to stretching and tearing of muscles and tendons in the neck. These injuries are seen in car accidents, and sports like football. Neck strains are not like neck sprains. Neck sprains are due to ligament (tissue connecting bones to each other) tearing, whereas, neck strains are due to muscle or tendon (bands of tissue connecting muscles to bones) damage.
Now, the symptoms for whiplash injury are tenderness, pain while moving head, stiffness while moving head, decreased range of motion, headaches at the base of the skull radiating towards forehead, feeling like muscles are knotted. The neck strain can cause concussion also, for which you will have to go to a doctor soon.
The best thing is that the Whiplash injury can be treated or it can heal on its own in sometime. For its soon recovery, you can use a neck brace or collar, ice your neck, apply moist heat to your neck, take painkillers like naproxen or ibuprofen. You can also go for other treatment like massage. So, if you have got this problem, you can go to a doctor for proper recovery options.