Brief Answer:
investigation is required

Detailed Answer:
Hello,

fever with uncontrolled shaking (rigor) is usually a sign of serious infection. Rigor has to be distinguished from chills. Rigor means rattling teeth, excessive trembling. Chills only feels like too much cold and mild tremor. Sometimes common infections like influenza may cause rigor but in most cases rigor means serious infection. Other symptoms and signs will determine the diagnosis. For example cough, fever and rigor may be signs of pneumonia. Abdominal pain, fever and rigor could be cholangitis or other serious abdominal infection.

Clinical examination and laboratory testing are important to determine the diagnosis. You'd better visit your doctor as soon as possible.

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Kind Regards!

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