cough? staying apart from the flock

[Trishkabob]

we have a 3 yr old JG who is generally top of the flock of 5. It has been very cold here, with a foot of snow last week, now warmer and melting. She has been keeping apart from the others though she knows they are getting treats (and eats happily when I give them to her). She won't follow them, roosts much of the day, and today was making an odd cluck/cough. I'm not looking to medicate her but wonder what, if anything I might keep on the lookout for?
thanks.

 

[Eggcessive]

I might catch her off the roost at night, feel her to see if she is losing weight, check her crop (of course the best time is in the morning to check for emptying) to see if she is eating, check for lice and mites, listen for any rattles, look for any facial swelling, eye or nasal drainage. It would be good to check poos if possible, watch her eating.