The patient is manifesting symptoms of malignant hypehermia (fevers, rigors, and myoglobinuria), which is treated by administration of dantrolene, immediate discontinuation of offending medication (which can include succinylcholine or halothanebased inhalational anesthetics), and suppoive cooling measures. While urine alkalinization, loop diuretics, and mannitol are appropriate treatment measures for rhabdomyolysis, the underlying problem in this patient is malignant hypehermia, which, because of its associated moality of 30% in severe cases, should be treated first and foremost. Malignant hypehermia is not a manifestation of anaphylactic shock, and therefore steroids and antihistamines have no role in its treatment.