Whiplash can be very painful and can greatly affect your life. You move your neck a lot more often than you probably realize - until you can't move it so well.
Your doctor will likely give you medications for pain, swelling and muscle spasms. To keep you neck from moving, you'll probably be fitted with a cervical collar, a soft thick collar that rests on your shoulders, supporting your head. You may be advised to use moist heat and ice packs as well.
Many people who have whiplash see a physical therapist who can help manage the pain and help you do exercises to strengthen the muscles and ease the spasms.