You’ll need to give them to him via syringe
https://www.backyardchickens.com/articles/safely-administering-oral-medications-to-all-poultry-and-waterfowl.73335/ another way is with tubing but you have to have tube feeding stuff. If you have the syringe or can get one get the 1 ml you’ll just have...
Right now you’ve done all you can brought him inside got him comfortable . Gave him activated charcoal, it does sound like he may have eaten something toxic especially since he’s having a hard time holding his head up. It’s just wait and see now. If no better by tomorrow and you can maybe a...