This case study presents the comprehensive evaluation and management of a 4-year-old male patient with phimosis who presented with fever, anorexia, weakness, and burning micturition. Upon admission, bilateral multiple renal abscesses and cystitis were diagnosed through ultrasound examination, prompting initiation of intravenous (IV) piperacillin–tazobactam combination and IV vancomycin. Due to concerns of red man syndrome, vancomycin was closely monitored, and a multidisciplinary approach involving specialists in pediatric infectious diseases and surgery was adopted. Sensitivity testing revealed Escherichia coli infection resistant to multiple antibiotics, leading to a switch to IV meropenem. Additional investigations for suspected mumps yielded negative results, emphasizing the importance of thorough evaluation. The patient's condition improved with appropriate antibiotic therapy, as evidenced by decreasing abscess size and resolution of symptoms. This case underscores the significance of tailored antibiotic therapy, close monitoring, and multidisciplinary collaboration in managing complex pediatric infectious cases, ensuring optimal patient outcomes. Additionally, the patient's complete vaccination highlights the potential for atypical mumps presentations. Resurgence factors include secondary vaccine failure, reduced vaccine effectiveness (85–90%), and lack of natural boosting from wild-type virus.