What Causes High Fever With Elevated CPK Level?

My sister aged 60 is having high fever from 102 to 104 for the past 3-4 days. Her doc ordered CPK blood test that came back with levels around 5000.She is having speech difficulties. She has been taking psychiatric drugs for the past 30 years. Doc as yet has not come to a definite diagnosis and says she needs a neurology consult. What you reckon doc?