I agree Scott, that looks like more than pouting
Are you running carbon? Leathers don't seem to like carbon for some reason but it still looks like more of a problem than that.
Still have that iodine you used for the clown's wounds? Do an iodine dip on it. Use enough iodine in a small container of tank water to *just* tint the water yellow-ish. Cut away any bad parts that are obviously disintegrating and then swish it around gently for 30 seconds.
If it really looks bad, cut the good parts into frag size, dip them and see if you can save it that way. Leathers will grow a new coral from any part of the coral that's fragged.
Good luck with it, Scott.
Alice