Have a sick hen please help

[Emerson01]

Hi so I have a very strange case. A couple of days ago I had a random person I don’t know drop a hen off in my yard. My assumption is they found her in their yard and saw I have chickens and assume she’s mine. I don’t know who’s she is or where she came from before that so I don’t know anything about her history. I came home from work today and she was hiding under a board a had propped up against the house. I’ve been keeping a close eye on her to make sure she’s doing well since I know nothing about her. I went to move her out and set her in the coop next to the food. I noticed the day she was dropped here and today as well her crop felt empty so I’m not sure she’s been eating much I know she’s ate and drank some but I don’t think much. When I saw her in there and was watching her I noticed a runny yellow substance was ran down her feathers underneath her vent. My immediate thought was a broken egg but I looked closer and it was also mixed with green and looked more like diarrhea possibly. I checked her vent and it’s clean and healthy looking immediately around it and the feathers look good. The trail of yellow starts about a half inch below her vent so the immediate area around it is actually good and clean. I am getting yogurt and probably gonna give her a soak in epsom salt. She’s definitely weak today as well I have multiple perches set up at different heights in the coop and she struggled to get up on one that was only about 6” off the ground. Her second night she was roosted up on my roof so before today she had no problem getting up in high places. Please let me know of anything I can do for her to help her get better or anything I can check to pinpoint the issue.

 

[nuthatched]

Have you separated her from your flock?

 

[Emerson01]

Have you separated her from your flock?

Yes I’ve separated her into her own area away from the coop with food and water I put some acv in the water and a supplement in the feed

 

[nuthatched]

Yes I’ve separated her into her own area away from the coop with food and water I put some acv in the water and a supplement in the feed

Remove the acv water. What's the supplement?
Is the yellow coming from her vent or below it?
I'd honestly put her down, a sick bird near your flock can kill your flock.