Need help with chicken ( rooster)

OK.. some of you know that I raise chickens for eggs. So few days ago, I let chickens out the am. Every chickens was fine. Then in the evening, I counted the chickens before lock them up for the nights. I noticed one was missing..( Barred Rock rooster). At the late evening before dark.. BRR showed up but walked slowly. I went and picked him up and hold him. I checked on him and found his right eye was shut and swollen. I brought him in the house and under light.. I opened his eye. noticed it was tear.. so I wiped puss and put him in other pen just himself. His eye keep shut but he keep itching and trying to clean it up. I put other hen ( same breed) with him so he won't be lonely. Today, his both eyes was opened. I noticed his right eye was smooth but black , bit swollen. Other left eye is fine.. Today he just stand quietly and take lots of rest with eyes close. Today I give a test.. I moved him and hen to the group in the other pen. The Rhode Island Red rooster attacked him. I wnet in and picked BRR quickly and put in small pen. I built a large temporary pen. I moved Him and 3 hens in large pen. He eats/drink well.
I am kinda worrying about lose him. He's only rooster and 3 hens I have ( Barred Rock). Do u think he's sick or is he trying to take plenty rest to healing ? What do u think?

Tricia