A 23-year-old man presents to the emergency department with severe pain and swelling in both hands. He reports similar episodes in the past affecting different joints. He has no history of trauma or recent infections. On examination, he is in distress due to pain, has mild pallor, and his hands appear swollen and tender without signs of infection. Laboratory findings are as follows: Hemoglobin: 7.9 g/Dl, WBC: 11,200/mm³, Platelet count: 340,000/mm³, Reticulocyte count: 10%. Peripheral blood smear shows Sickle-shaped red blood cells. What is the most likely diagnosis?