My chickens got sick. Swollen eyes, runny noses. wouldn't eat or drink. Also had foamy runny poo. Could be bad feed or are you watering them in those little giant metal gallon waters? I used them for a while and my chickens got sick. Sounds like the same thing. We used terramycin and took the metal waters containers out which I was told they contain lead. I now use plastic ones. With the terramycin you can't eat the eggs for a while though. For bugs we use the diatomaceous earth food grade. We haven't had a bug problem since. Make sure it is food grade though. It helps with worms also. Hope this helps. Sorry for your loss