my chook is quiet and not interested in treats this morning

i have a hybrid blue chook.  she is aobut 5/6 months old.

she is usually interested in any and all treats, but this morning she is quiet and withdrawn, and let the others chase after the tomatoes ( she is usually the first to pick up the tomatoe and run!) and seedless grapes.  i have just seen her lie down in the corner of the run and try to sleep.  she is walking around really slow.

doesnt seem to be anything else of note - just her behaviour.

have no idea at all what i should be doing about it?

my other blue hybrid died unexpectedly 3 weeks ago.  she had a strange sounding cough and seemed to be fine in morning, but was dead in evening.

hoping i am just being over anxious here!

any suggestions?

she did give me an egg today, and has been laying without problems.

just checked on her again, and she is sitting in a corner, in the shade lookingn very sad and withdrawn

dont think its the sun that is affecting her - lol in UK.  However, there is plenty of fresh water available for the chooks

any suggestions??

am still really worried about her.  she alternates between lying in a corner with her eyes closed and walking slowly around the run.  absolutely no interest at all in what is going on

just wondering if ANYONE at all could help me out here.  i am a completely new chicken owner - got my first 5 chooks mid march, one has already died and this other one is not doing too well today

i have no idea at all what i should be doing for her, with her or what i could or should be looking out for.

she is very quiet and withdrawn, not interested in eating - but she is drinking.  seh is moving around very slowly, this afternoon seemed quite sleepy lying down in teh corner of teh run.

there doesnt seem to be any other symptoms

help / advice welcomed
 

yes, i dont think she has eaten today.

i have just been out and picked her up and had a good look - there is nothing obvious

her feet are clean

her eyes seem bright enough

her feathers seem in reasonable condition

there was nothing between her legs - she did lay today

however, her crop is empty, and when i picked her up she vomited A LOT of clear fluid

i dont have any eggs left!!, i gave away the last of them today :(  will have to wait till morning but its worth a try.  maybe i could mash it up with some oyster shells and some grit?

i have also been giving them some natural yoghurt, but sods law, they got the last of the yoghurt yesterday :(

am really worried about her, but more so because i am so new to this, and have gotten really attached to my girls, and feel soooooooo distressed because one of them is unwell

thinking of you!

maybe some of the other experienced chicken owners can pitch in?