According the the OP and the pics... I would treat with Tylan or put them down. Here are your two options. I underline treat because you won't be cureing it at all. Just making the symptoms better. Like if your back hurts all the time and you take aleve or whatnot... you aren't cureing or fixing the ailment... just making it feel better.
Because of that you may want to put them down. If you ever get more chickens... these will only make them sick EVENTUALLY. Alot of people think "well it's been three months and no one else is sick" Yes they are. They just aren't showing yet. They are still spreading it around.
Personally... I would have them tested by the state... and report the breeder. Everyone gets a sick bird in their flock but not honest person would SELL IT!!?!?!?!??!!? Blows my mind.
When people say "cold" with chickens they usually mean MG which is a respitory infection SIMULAR to a humans cold. Again... you can treat it with Tylan.
I'm sorry as a newbie you are having to deal with this. Personally, I would put them down. THey don't look too good. I'm sorry. They are suffering when they are huddled up with their heads tucked in like that.
Again... don't let this "breeder" get away with it. Give them a piece of your mind at least. I don't live far from GA.. matter of fact, I'm going down to sell a rooster today.... give me his name and I'll make his like h*ll!!LOL