Thank you @mountaintoppufferkeeper and @Fish Folk! It's amazing to have you both as a resource. That growth on this hairy puffer looks very similar!
This may be coinciding with a lack of diversity in her diet. I have been slacking on my snail breeding since I've had scuds outcompeting them for food in my snail tank. She lives with a large colony of cherry shrimp, but I think she is too slow to catch one very often. So it's mostly just been bloodworms.
Just placed an order for some more snails to try and rebuild their population (and attempting to get rid of the scuds). I'm also going to try out the vita chem. I'll post here if anything changes!