Runny Poop, Lethargic, Sleeping Outside Away from Flock

[JeepersCreepers]

I've never had a sick chicky before. I have a 5 month old Silkie who is having runny amber colored poop, acting lethargic, and tonight I discovered her sleeping outside the coop away from the flock. I just tonight started Poly vi sol (w/o iron) in the flock water. I have 4 other chickies who are not showing any symptoms. Should I separate her? Do I need to find a vet? What help can I give my poor little Silkie?

 

[Wyorp Rock]

I would separate her and put her in a warm quiet area.

Is she eating and drinking? Has she eaten anything soured, moldy, rotten or that has gone bad?
What type of feed are you feeding her?
Are the other 4 silkies or are they a larger chicken, are they keeping her away from the feed/water?
Have you changed your feed/treats, added new chickens, have there been any changes to the environment/coop/run, have you used any cleaning products in the coop/run, any treatments for worms/lice/mites?

 

[JeepersCreepers]

So far she has still been eating and drinking from what I've seen-I was not able to observe yesterday though. I feed them the Dumor crumbles from Tractor Supply.I did recently add scratch and mealworms. There is one other Silkie. The others are an EE and 2 Black Sex LInks. The other Silkie is dominant but both Silkies usually dominate the food. I recently expanded my run and did create some stress for the girls in the final installment. I am planning to call my vet to see about doing a fecal test for parasites. Should I stop the scratch and worms for now? Could it be too much "junk food"?

 

[Wyorp Rock]

How old is she? Could it be coccidiosis?
Does she have access to grit? As a general rule treats shouldn't exceed 10% of their daily intake. Scratch and mealworms won't hurt them unless they have gone "bad".
Separate her so you can observe her water/food intake. Hydration is important if she is lethargic. If she won't eat her crumbles you can give her some scrambled/hard boiled egg or tuna and see if she will eat that. I would think the poly vi sol in the water would also be good.