My husband has these acute symptoms intermittently and can be spaced by months: Sudden onset of rigors, temperature of 101 - 102. A few times we have had to call an ambulance because he vomits, the rigors become violent and becomes incoherent. After a round of antibiotics and Tylenol, the symptoms subside within 3- 6 hours. No doctor has been able to tell us what is causing this.