A stiff neck without other symptoms might be caused by minor muscle strain from sleeping in an odd position or looking down at a phone too long.
If your child has a stiff neck along with a fever and a headache, it could be more serious. For instance, meningitis is a rare infection of the covering of the brain and spinal cord that can cause a stiff neck, headache, and fever.
What to Do
If your child has a stiff or sore neck but no fever or other symptoms:
put a warm moist cloth on the neck as often as needed for pain