not sure on the breed but my chicks about four weeks old and today i woke up to check on them like i do and I saw that one of them was rather larger than the others. This happened between last night about 8:30 and today around 10 ish. All the other birds are fine I checked them all. Absolutely nothing is wrong with the other chickens. this one other than it's swollen on one side it wants to lay down and it has a runny nose. Its almost like there's a bunch of air in it. I want to say this is a ruptured air sac because it is just air and the reason for it might be that they they like to fly or run around there's 8 of them so they tend to Peck at each other. It is still eating and drinking so it's not too bad to the point where I feel like I need to bring it to the vet but it is constantly just screaming. Its poops look the same like any other day solid a little runny or the normal but other than that it's fine. I have not treated but since I think I'm I'm almost 96% sure I know where it is so I'm going to try to treat it myself and then if it all goes well he'll be fine if not I'm going to bring them to the vet. They have wood shavings for their bed. Any help would be very appreciated.