HELP! Rooster acting strange?

Hello everyone! I came home from work today and found my big rooster standing in the coop which is very unusual for him. I left him and just came out to check on him and he is going downhill fast. I tried to offer him egg yolk syringe and he reacted almost immediately with what I would call a seizure. He was completely fine yesterday. Any and all opinions are appreciated. Thank you.

Edit: thank you everyone who took the time to respond and give advice. I brought him in the house to the bathroom with blankets and a pillow and shut the lights off and he passed on his own. I’m thankful he didn’t stuffer for too long. Give your Roos a big hug from me ❤️