I’ve got 6 bantam birchen Cochin chicks. 2 of them have had pasty butt since I got them(about a week). I’ve been cleaning thier bums regularly with warm wetted paper towel sponge. After that I put coconut oil on and around thier vent to soothe and loosen their fluff. Is there anything more I can be doing ? These two are starting to be noticeably smaller then the others. What helps pasty butt?