I got 3 chicks from the feed store three days ago and all was fine for the first day or so. I was of course on the look-out for pasty butt and they were scared so they kept showing me their back ends (we're working on that). It was yesterday that I noticed a bump on the back end of my Welsummer,  below the vent. It looks like a big browish-red wart. I should also mention she did jump from my hand that morning and land on the counter and fall to the ground (about 3 feet). She was fine afterwards, but today she was slow getting going so I moved her to quarantine. Here's the best pic I could get through the feathers. Any ideas what it is? Should I continue quarantining her? Should I see about a replacement before the chicks are too old to mix? Thanks!