A 4-year-old girl with a history of high-functioning autism spectrum disorder (ASD) and no significant medical history presented to her primary care provider for cough with confirmed SARS-CoV-2 infection. Two weeks after diagnosis, she began a 10- day course of amoxicillin-clavulanate for lingering sinus symptoms, which ultimately resolved. Four weeks after diagnosis, she appeared less interactive and engaged in uncharacteristic behaviors such as lying on the ground and repeatedly covering her ears and eyes. Over the next few weeks, she exhibited a dramatic reduction in meaningful speech, increased repetitive purposeless movements (jumping and rubbing limbs on objects), increased repetitive speech, grimacing, gait changes, ambitendency, and urinary incontinence.