It would probably be dead by now if it were truly choking. If not, just try and make sure his airway isn't blocked. Maybe you can scoop it out or add just a teeny weeny bit of water to soften up the stuck food. Don't put it in his windpipe though.
Hi! I'm really new to this, too, but what did it eat? If it wasn't regular chick food, maybe it needs some grit to break something down?? You could try getting some sand or dirt from outside and see if it eats it. This may not be great advice, but it's all I can think of. Maybe some of the more veteran members will chime in soon with some better advice, but in the meantime, it's worth a try! At the very least, it's a bump to keep you on the front page