What Causes Severe Headache Along With High Fever?

my best friends son was admitted to the hospital this morning with extreme head pain and was talking in numbers instead of words. he has been running a high fever off and on for a week and has had 2 visits to the emergency room during that time. he was put on antibiotics a few days ago for possible appendix problems. now they have him on a breathing machine in icu and act like they don't know whats wrong.