A 9-year-old child complains of painful rashes that appeared on the lips. Objectively, the vermilion border of the lips is edematous, hyperemic, and covered in cracks and numerous bloody scabs. On the skin around the lips, there are small blisters with a serous content. In some areas, the blisters merge together. Maceration and weeping of the skin are observed, especially in the corners of the mouth. What is the most likely diagnosis in this case?