8 month old chicken with poo sticking around its vent! Help!

[pittsfordchickens]

We have 6 hens and 1 of them has been missing feathers around its bottom and now has poo sticking around and in its vent. it has been going on for about 3 weeks and keeps getting worse. tried sticking her in a tub of water but it didnt change anything. she is laying fine and eating good. im stumped... is this pasty butt or what?!
Please help,
thanks

 

[seminolewind]

cut the dirty feathers off.

 

[LiLRedCV]

After you clean her up, add unpasteurized organic Apple Cider Vinegar (ACV) to her water. Should be about 1 Tbsp per gallon... Do this every time you refill the water. It'll help tremendously!