Suddenly very ill Rooster

[StupidBird]

One year old rir-bo cross very healthy rooster until last night; wasn't on the roost and just thought the hen he's in isolation with booted him off the roost (in isolation due to conflict with my big ol' head rooster)
This morning, just now, all somewhat hunched but limp, not moving. Comb is purple-dull, not eating even corn, or drinking. Breathing is very slow. Appears cold. When I moved him inside, clear fluid dribbled from beak and made a very sad little noise. Crop is loose, somewhat spongy.
He was out of the enclosure at will in the garden yesterday acting all normal; being out in the garden is also the usual routine.

I'm thinking injured or sick - something smells like an injury but I can't find it; doesn't seem to be sour crop.

Will look again.

 

[StupidBird]

7:57am He just lays there on a bath towel, head over the water dish. Kinda tipped over onto the right wing, outspread, and left tucked under. Bones feel ok in wings and legs. No vent problems. I'm going to try spooning some water if he seems interested. No discharge at eyes, vent, nostrils. No more dribble.

I still smell a sort of blood smell but can't find anything. No poops since brought out of pen.

 

[StupidBird]

Upon another examination, the crop is now definitely larger than earlier, spongy soft. Massaging it makes gurgling noises and he dribbles a bit.

Sour crop? It rained yesterday and the bird could've found something truly nasty to eat. This would be a relief if correct as it is not communicable although still serious. Adding Braggs apple cider vinegar to water and offering live culture yogurt per other posts and previous experience.

Anything you have to offer will be appreciated!

 

[StupidBird]

11:48am Head down, eyes shut, comb dark; bird is unresponsive and breathing very slowly. Being kept warm, with water and treats, dark and quiet bathroom. I don't know what else to do. If the bird doesn't improve by tomorrow I will probably put it down - I'm sorry.

 

[StupidBird]

12:08 noon. He just fell over and died. Unreasonably, I feel terrible. This was my DH's fav that he wanted as a pet. Now off to bury it.

Please let me know if you all have anything to advise for the rest of the flock. I will be out of town soon and will be having my son look after them...I am feeling rather low about this.