One rule is to always include "the worst-case scenario" in your differential diagnosis and make sure you have ruled out this possibility based on your findings and patient assessment

One rule is to always include "the worst-case scenario" in your differential diagnosis and make sure you have ruled out this possibility based on your findings and patient assessment. Your goal is to minimize the risk of missing unusual or infrequent conditions such as meningococcal meningitis, bacterial endocarditis, pulmonary embolus, or subdural hematoma that are particularly ominous. 

Address the following question:  What are the "red flags" in this case? Based on your pertinent key findings, what is "the worst-case scenario"? What lessons did you learn from this case that you can apply to your future professional practice?