Infected chicken

I purchased 5 hens last week to set eggs for me and one now has some type of infection. It may be where the hens have been fighting. Her eye has a clear discharge that looks like it has air bubbles in it. It doesn't look pusy(sp?) and I don't see a wound but it has an infected smell, there is definately infection somewhere by the smell. Could there be a respiratory inf? I can't tell that she's breathing funny. I separated her from the rest, she's in a large dog carrier with food and water. The only antibiotics I have here are injectables of Pen G, Gentamycin, LA 200, Naxcel and Baytril. Will any of these work for chickens or do I need to make a run to the store tomorrow? I have no clue how to give a chicken a shot. She is very skinny under her feathers, just feels like bones. She has food and water in the carrier and last time I checked her she had drank a good bit of water. She had been doing nothing but hiding in the chicken coop so probably hadn't drank for awhile. Any advice would be appreciated.

Thanks, Lana