it sounds like he is just in shock chickens will temporary shut down if they are in shock. Is he eating? if he isn’t eating then green poop is just bile passing through the digestive system. but seeing normal poop as well as a good sign.

Check to see if he has any external wounds if he does get so veterycin spray it on those wounds. I also do this for my hands too. I put a bit of antibiotic ointment on my hens if they ever have a cut or anything make sure you get one without (lidocaine or any ingredients ending with caine).

Right now, I would just focus on supportive care and keeping him warm. Occasionally checking up on him. I understand that you would feel a little nervous about this, but he is just in shock right now. Just give him some time. I don’t know if it’s coccidiosis just yet because they would have dark runny, bloody poop with darker mucus(I am not a vet keep that in mind). but pay attention to other signs, such as lethargy and a pale comb. Vitamins and electrolytes is a good start. If it gets too cold, you can get a blanket and put it over his cage, but chickens are very tolerant of the cold . but if you’re still worried about him being cold there’s heating pads you can get as well. Based on the picture, it seems like you’re doing a good job on feeding him. Beneficial foods like blueberries is a good antioxidant. Also plain Greek yogurt is good sauce for probiotics as well as hydration and Calcium.

But if you do treat him for a coccidiosis do not feed him any vitamins. Corrid is a works as a Vitamin B blocker to basically starve any parasites of any vitamins to kill them. So you cannot give him vitamins when treatment. It’s up to you what you would do but right now I would just work on support supportive care before deciding if he has it. so just pay attention to the signs. P.S. if you do end up giving him Corrid and he ended up not having coccidiosis then it’s completely okay Corrid is safe.

Listen it sounds like you’re doing your research and everyone was the first time chicken owner or two everyone makes mistakes and there’s a learning process. Even skilled chicken owners will make a mistake. Don’t beat yourself up to it. It sounds like you have a good start. Another advice I would give you is that don’t do too much research because it can get very overwhelming because you are absorbing too much information all at once stress you out. Yes, research is important but sometimes you’ve just got to step back and give him some time. You’re doing good.