I have 14 new chickens. 2 are 6 mo old the rest are about 3 mo old. I've never owned chickens so I'm at a loss as to what to do. Most of them have a strange gurgly sound and occasional cough. A few have shown occasional watery eyes and slightly runny nose (clear) but it's all very minimal and comes and goes (except the gurgling and coughing) also they all seem to have a strange, almost sour smell to their bodies and mouth. My rooster has some discoloration around his neck area from wiping his face. The poop looks great, text book chicken poo! Appetites are the same. They drinks lots of water, and are still active!! Although the 2 -6 mo old hens have stopped laying and my rooster has stopped crowing 
I first tried to give antibiotics in the water (duramycin10) for 5 days with absolutely no change. Tried electrolytes/vitamins in water, no change. Fed garlic, no change.
Now I'm sitting writing this thread and reading directions for VETRX and WAZINE17 (wormer) so that I can try them tomorrow.... I'm at a loss! What is going on!? No environmental changes, I'm in Houston so it's not cold, their coop is very well ventilated and they have more than enough room so it's not over crowding. I use pine straw from our yard as the coop bedding. Any ideas??

I first tried to give antibiotics in the water (duramycin10) for 5 days with absolutely no change. Tried electrolytes/vitamins in water, no change. Fed garlic, no change.
Now I'm sitting writing this thread and reading directions for VETRX and WAZINE17 (wormer) so that I can try them tomorrow.... I'm at a loss! What is going on!? No environmental changes, I'm in Houston so it's not cold, their coop is very well ventilated and they have more than enough room so it's not over crowding. I use pine straw from our yard as the coop bedding. Any ideas??