Swelling on hand that keeps filling with fluid or pus could be due to an infection, possibly from a cut or insect bite. When it drains and fills back up, it could indicate an ongoing infection. It's important to keep the area clean and dry to prevent further complications. I recommend gently washing the area with soap and water, applying a clean bandage, and keeping your hand elevated to reduce swelling. However, if the symptoms persist or worsen, it's best to seek medical attention for further evaluation and possible antibiotics.