After spending her vacation at the seaside, a 25-year-old woman developed complaints of weakness, myalgia, fever of 38.5°C, and pain and edema in her radiocarpal and elbow joints. Objectively, she has an erythematous rash on her cheeks and nasal dorsum and ulcers on her oral mucosa. Serological testing detects an increase in the titers of anti-nuclear antibodies to native DNA. What is the most likely diagnosis in this case?