Is my rooster sick?

[Dubb]

My rooster's crow started getting weak and subdued and he has now stopped crowing entirely and I heard him sneeze this morning. What could be the problem and what should I do? He is in a pen with 11 hens.
My rooster is a Rhode Island Red and is less than 1 year old. He has been crowing with a strong voice for several months now. This afternoon I heard him wheezing some which makes me think he is conjested. I'm not sure what to do with him, I don't want to loose him. I've had him since he was 2 or 3 weeks old.

 

[RedRoosterFarm]

I know when its cold here that my roosters(small ones) loose their crow until it warms up a bit. Also maybe its an age thing? Learning to crow maybe?? I wish I could help. Might want to seperate if he is sneezing. Antibotics too.