on high alert, any insight appreciated!

[das fisch]

Yesterday morning, went out about 6:30/7:00 am to let our 6 RIR's out. as usual they all were anxious to roam in their enclosed run and came storming out. They've been molting I believe so we're down to about 4 eggs a day, food was full, water was full and clean. went back to check on them a few hours later and one was laying dead in the run. recovered her, no obvious sign of trauma, did notice crop seemed to be empty though. So obviously we're watching the rest closely.
Did notice one other was a bit different, but was out and about with her sisters.
Last night got our first snow, so when I let them out this morning they were hesitant as they've never seen the white stuff before. They were hatched on easter of this year.
Eventually they came out to free range and had a blast in the leaves and snow, but after a bit one retreated back to the coop and took a seat on her roost.
While checking for eggs I found one bloody poop, see pics below. The one who was acting slightly different seems to have a rough patch on her neck, molting maybe, and tail area (above vent) seems to be a bit enlarged, but not much if any really.
now i can't connect the patchy hen with the poop, but it we're being cautious after yesterday's unexplained death.
any help would be GREATLY appreciated, don't want to lose another.
other details;
-5 remaining RIR's, all from same batch (brought home day after easter)
-always clean, fresh water; ACV in every other jug
-layer pellets, ocassional snacks
-free ranged when we're around

pics:

notice patch under waddle/neck

a few views of bloody stool

 

[PunkinPeep]

I'm not sure i would identify that as bloody stool.

Have you checked for lice or mites?

Did you notice whether the chicken who died was unusually light?

 

[das fisch]

haven't checked for lice or mites in a while, and definitely did not with the one who passed away... didn't think of it.
will check the others here soon.
she did not seem that light, not noticeably anyway, just empty crop.

we're probably over reacting, but rather be safe than sorry.

added: just checked the one pictured above, no obvious signs of lice or mites that I can see. vent areas is clean, does not seem to be lighter than the rest. we had 3 eggs out of 5 birds today, but there is signs of molting (feathers in coop) so i attributed to this. I was thinking she was molting. they have never been treated for bugs as we've never suspected an issue. coop bedding, pine shavings, is stirred regularly and changed when it seems too soiled or we have a stretch of humid weather or rain. does anyone treat for lice/mites if suspected but not found? will check all others tomorrow.

 

[PunkinPeep]

It's always possible that she had something you couldn't detect - a heart attack or whatever. I know it's so disturbing for something like this to happen. I'm truly sorry, and i hope the rest of your birds are just fine.

 

[silkiechicken]

The poo doesn't look like what I'd typically say is "bloody" poo. Just a stained bit of urates. The feathers on the hen just look like moulting and with 4/6 possible eggs a day, that is still very high for this time of year. Just keep an eye on the rest and if they seem fine, they are probably fine. Sometimes birds just die for no foreseeable reason. Heart attacks and aneurysms are not uncommon, especially with a change in environment/weather.