Final answer:
Head-bobbing in an infant can be caused by shaken-baby syndrome, which can lead to brain swelling and retinal hemorrhage, as well as other serious medical conditions requiring immediate attention.
Step-by-step explanation:
Head-bobbing in an infant can be a serious indication of shaken-baby syndrome, a form of physical abuse resulting from violently shaking or causing impact to an infant's head. Symptoms of this syndrome include brain swelling and retinal hemorrhage. Other potential causes for head-bobbing or unusual movements might include neurological disorders or injuries from accidents, such as contre-coup injuries or fractures to the skull that can be life-threatening. It's also critical to consider symptoms of early onset disease such as apnea, bradycardia, hypotension, irritability, or late-onset disease, such as seizures, bulging fontanel, stiff neck, hemiparesis, and opisthotonos. In clinical cases similar to the scenario of an infant named Olivia, symptoms like excessive crying, irritability, light sensitivity, unusual lethargy, and vomiting could suggest serious medical conditions that necessitate immediate medical evaluation.