Kaiden is a 3-month-old boy born at full term with a birth weight of 3.2 kg. He is breastfeeding and thrives satisfactorily. He was admitted for sudden onset of high fever up to 39 °C for 1 day. Her mother had mild upper respiratory symptoms, which has been resolved a few days ago. Kaiden did not have any respiratory symptoms. Apart from the fever, he appeared well. His feeding was normal, and there was no vomiting or diarrhoea. He passed urine normally. He was given some antipyretic, but the fever persisted; today, the temperature has risen to 40 °C. He was found to be more irritable and behaved unusually; hence, he was brought to the emergency department. Physical examination was uneventful, and he was admitted despite the absence of focalising signs for the infection. His nasopharyngeal swab for microarray of respiratory virus panel was negative. His urine test for nitrite was positive, and the leucocyte was 1+. What is the problem with Kaiden and how would you manage him?