What Causes Astasia With High Fever?

my friend is male, 36 years old, and has been confined in the hospital for 17 days so far. her initial tests ecg, chest xray, blood tests turned out normal. he will undergo colonoscopy and other tests. he was rushed to the hospital because his legs grew weak and he could barely walk. he has maintained a high fever - 38-39 degrees and has chills whenever the i.v. pushed paracetamol would lose its effect. he has been a heavy smoker and drinker for years. what could be wrong with him please? thank you