A 32-year-old woman presents to the emergency department with a four-day history of high-grade fever, severe headache, retro-orbital pain, and muscle aches. She also reports significant fatigue, nausea, and decreased appetite. On the second day of her illness, she developed a skin rash that started on her trunk and later spread to her extremities. She mentions a recent trip to a tropical region. On examination, the patient appeared lethargic and febrile with a temperature of 39.5°C. Her blood pressure was 100/70 mmHg, with a pulse of 100 beats per minute. The rash was erythematous and maculopapular, sparing the palms and soles. Petechiae were noted on her arms, and a positive tourniquet test suggested increased capillary fragility. Laboratory investigations revealed leukopenia with a white blood cell count of 3,000/μL, thrombocytopenia with a platelet count of 90,000/μL, and mildly elevated liver enzymes. Based on her recent travel history, you suspect dengue in this patient. Of the following, which is the most common symptom of dengue?
