FAC! (Funny acting chicken)

[MyCritterAddiction]

I have a RIR that is acting strang and I'm not sure what's wrong. She is about 5-6 months, not laying. She has always been quite, sweet, and reserved somewhat from the rest of the flock. The last 3 weeks she has began wondering farther away from the flock, loves to be around me, losing weight and looking pale. She is eating and drinking and loves to free range. She just doesn't LOOK or ACT healthy. I have looked for mites, none. Dusted everyone with DE just in case. Coop also dusted well. I have added electrolytes and probiotics and apple cider vinegar to their water! Even added DE to the food yesterday. I have noticed a little poo on her backside today, but when she pooped, it looked like okay; no worms or blood just a little watery. What am I missing? I don't want to lose this sweet girl!

 

[Fanci Feathers Marans]

The generally accepted thing to do is to quarantine with food and water. Check everything: eyes, nose, vent, foot pads, under-wings. Everything.
Has she ever laid an egg?
Worms don't always appear in the poo. If it does not seem to be spreading... you might try worming, I don't think it will hurt. Especially since she is eating and still losing weight.