I just checked all my nine chicks, and two others also had dried poo stuck to their butt feathers. But theirs wasn't white, and they were running around and acting normal. I cleaned them off and put vaseline on.
I did mix some plain yogurt with scrambled egg & put it in with their ff, and most of the chicks seemed to like it ok (no one liked the yogurt plain!).
The one I posted about first just stands in a corner and sleeps. Should I try giving her some sugar water, or maybe some sugar water mixed with yogurt?
My understanding of pasty butt is that it is heat related stress. The things I have found that have helped clear it is fermenting their feed, are you fermenting medicated starter or non medicated starter? Before I fermented we added some ACV to the chicks water and that cured the pasty butt within a day.