Is Pudding getting any milk products other than the yogurt? Cat's don't have the enzyme to digest milk, so they can get the poopies if they drink it. We have 10 (yes 10!) indoor cats. Only one of them shows any interest at all in milk, but we can't even turn our backs on a bowl of cereal or there she is, lapping up the milk. Of course, she pays the price later!
As for keeping her fanny clean, try cheap, unscented baby wipes.
As for keeping her fanny clean, try cheap, unscented baby wipes.