Lathargic Chicken with oozing vent? Help

[Pobutt]

One of our chickens has a watery fluid with white lines in it coming out of her vent? She is also very lathargic. Does anyone know what that is? My flock is being treated for mites. Could that have anything to do with it? Worms? I feel like I'm going to lose her.

Please help.

 

[Dar]

is she still in the coop?
is she eating at all?
all the info you can gather will help us help you if we can pics are great

 

[Pobutt]

She's in the coop in a dog crate on a shelf so the other chickens can't get to her. I put oats yogurt and mashed bananas in her crate last night and this morning it was almost all gone. I gave her some water with a little sugar in it. This morning when I looked at her she was quite perky and wanted out of the kennel. I'm not letting her out until I get a stool sample back from the vet tommorow. This morning I gave her some more oats, scrambled eggs and yogurt. She ate that so I gave her some scratch and her normal food. Her crop is quite full. She's being a little piggy. I looked at her vent again last night before going to bed. I was going to try to get a sample of it to take to the vet but nothing would come out. After my son comes home from school today I'm going to look at her vent again. I can't believe the improvement from yesterday. I called a lady and she said the insecticide she's being treated with for mites could've caused her to be a little sick.
Is that possible?
I would post a picture but there's nothing to see right now. If she starts oozing again I will.