What is wrong with my ducklings vent?

[psyduck 22]

My duckling's vent has been looking bumpy and red (see picture) for about a week now, and I'd like to know whats wrong with it and how to fix it.

The duckling is a little underdeveloped compared to its sibling, but is still growing and seems otherwise healthy.

 

[Miss Lydia]

My duckling's vent has been looking bumpy and red (see picture) for about a week now, and I'd like to know whats wrong with it and how to fix it.

The duckling is a little underdeveloped compared to its sibling, but is still growing and seems otherwise healthy.

Welcome to BYC,
that lil vent doesn't look too worrisome what are you feeding your ducklings and how does the poop look, are you using heat on them and at what temp? sometimes too warm a temp can cause them to have runny poo and maybe that's why it's lil vent looks puckered you might try using some Prep H on it it's help with swelling it just looks to me it may have just a tiny prolapse. Here is the rec temps for ducklings 1 st week 85* then each week there after drop the temp 5* till they are fully feathered.