So my four year old chicken is not doing too great. Over the past 4 days she's gotten very lethargic and barely eating, drinking, and having runny stool. Today, I bought some electrolytes / probiotics and fed the mix to her with a syringe. She's now in a box in my living room. I did a visual inspection and found something very odd just forward of her tail feathers. It looks like either a huge "pus bump" or a very very thick/wide feather trying to grow its way out. Around the bump is all black. If I try to touch it, it's obvious its causing her pain. I poured some hydrogen peroxide around the area. Does anyone know what this could be?