My 9mo silver laced Wyandotte has a mysterious wound on her bum. It was bleeding when I found her. It's about 2" below her vent. I soaked her, neosporined it (w/o pain reliever), isolated her to a warm and dark space. She's eating, drinking and pooping fine. Not tired. She stays with 5 other girls and they've all seemed fine. No breeches in the coop/run. What could this injury be from?