A previously healthy 6-year-old Hispanic female presented with a three-week history of bilateral proximal limb weakness following an empiric ampicillin course for suspected strep pharyngitis. The patient presented to the ED after outpatient workup showed elevated AST/ALT (500s). Physical exam showed proximal symmetric weakness in the deltoids, biceps, triceps, hip flexors, and extensors, positive Gower's sign, and bilateral pelvic tilt with waddling gait. Serum testing showed elevated AST 455, ALT 653, and CPK of 18290. Workup was notable for elevated ANA and dsDNA autoantibodies, elevated TSH, and low vitamin D and complement. EBV panel showed elevated VCA IgG (525), early Ab IgG (44.9), and plasma qPCR (201). Given the elevated ANA and dsDNA, suspicion was greatest for myositis. EMG revealed evidence of irritative myositis. Serum antibody testing for myositis showed elevated anti-HMGCR Ab (>200; measured three weeks post-symptom onset). The patient showed improvement of motor strength after treatment with prednisolone and monthly IVIG therapy.