Looks like some kind of sinus infection, respiratory illness.
Duramycin-10 might not be powerful enough to handle it, but I don't know, only saying that there are different antibiotics for different diseases/illnesses.
How long have you been giving him the Duramycin? If its only been like two days, then I'd say keep giving it to him, but if its been more than a week and the lump is growing, you'll need something else to fight it. I agree with what Eggcessive has said above too.
If you can bring him into some warmer place for now, it might be a good idea. Cold temps make chicken's bodies have to work harder to keep systems going well, so that could help to bring him in a warmer place. It does look like coryza to me, but I'm not a vet and definitely not a chicken health pro.
I don't know if this helped my hens any when I had a respiratory infection going through my flock but I treated them with a 'sauna' with oxine AH. no activator. Here is a link to where you can purchase it:
http://www.amazon.com/Bio-Cide-International-Oxine-AH-Gallon/dp/B000HT7H8W
If you do some web searches on it here you'll find more information about treating respiratory illness in chickens with Oxine AH.
Prayers and recovery for your sweet roo!