Rooster acting lethargic?

[Rigal082]

My rooster Dominique has been acting very tired and slow all day. This morning when I let him out, he was slower to react, even when I set out the food. His crop appeared completely empty like normal, but his comb was slightly more tilted and purple than usual. This afternoon I came out because I saw him bowing his head slightly with his eyes closed and tail lowered. I am doing a deep clean of their coop today just in case there are parasites. He hasn’t drank or ate much at all, but randomly after resting he perks back up, lifts up his tail like normal and walks around like nothing is wrong. I’m worried about him, I had been away for 4 days, and yesterday afternoon when I came back, he seemed fine. Only today did I learn my caretaker had forgot to let my chickens out and they sat in their coop all day. Their coop is ventilated so air was able to get through. So now I’m stressed and ticked off. Perhaps this could be a vitamin deficiency?
Here are some photos of him I took today:

 

[Eggcessive]

I would try to get some Poultry NutriDrench today and give him 2-3 ml very slowly. Mix some feed with a lot of water and try to tempt him to take that and drink water. He could be dehydrated. Electrolytes, pedialyte, or Gatorade could be substituted for the NutriDrench, but it works quickly along with getting water. Offer some scrambled egg as well or other preferred treats. Did they have food and water inside their coop? Was it light in there?

 

[Rigal082]

Thank you so much for replying! There had been a small amount of food in the coop when they were left in there, but no water. Sunlight is able to shine in the coop quite well.

 

[Rigal082]

Update: Yesterday, I brought in Dominique to a quarantined area where he can rest. I gave him electrolyte water and a small dose of intestinal worm medicine. Today I woke up to him crowing! He did not crow at all yesterday, but has been very vocal today, as usual, so I figured this is an improvement. He has more of an appetite today and a little perkier, but he continues to have these random moments where he slumps over and dozes off before snapping back up to eat and crow. I’ve never experienced behavior like this in a chicken before and unsure of what steps I should take next. Here are some photos I took of him today:

 

[Rigal082]

Update 2: I’m beginning to suspect Coccidiosis in my rooster due his increasing immobility and green watery poop. His comb is growing a darker purple and he lays completely down on his side. I’m giving him antibiotics while trying to get my hands on some Amprolium. What else can I do?
Here are some photos I took of him and how the poop looks: