Got a new chicken but his eye is swollen shut

[smw18]

So I went to a swap meet, I know not smart, and got a few little bantams. Well, when I got them home, I noticed one had its eye swollen shut. I was thinking it maybe from the other little bantam roo he was in with but wasnt sure. So I was wondering if someone could tell me how to fix it.

 

[smw18]

The stuff on its beak was from the fact they kicked all their feed into the water, just about and he drank after and just never cleaned his beak.