I got 3 pekin hens a little over 2 weeks ago and a couple of days after, i noticed one had a bit of black rear. I looked into it a little, decided it was just pastings, and cleaned her up and let her on her merry way. A few days ago I noticed it returned, but this time she looks quite low to the ground. She doesn't really act any different from the other ducks. I did put her in a warm bath to see if that would do anything but it didn't seem to.I haven't determined if she is laying eggs. I usually get 2 a day, but i don't know which ones they come from. I'm wondering if there is anything wrong with her, or if she is just fat. Is there anything I can do to fix any problems she might have, or does is there any problem at all? I'm quite new to this and am open to any and all advice.