Question: What is recommended for a mixed flock (layers, pullets, ducks) when I have several coveted Silky chickens with what I believe to be CRD (bubbles coming from eyes). Symptoms/Signs: They are still eating, drinking, etc., but have bubbles coming from their eyes. They scratch at their eyes, and one Silky this morning was moving her head back and forth rapidly almost uncontrollably. Treatment Used Thus Far: I have been using Terramycin (labeled for the treatment of CRD) to no avail. I also cleaned the eyes and nasal passage with a warm cloth. What is the duration to make progress using Terramycin, as I have been using it for a couple weeks now? I noticed it says not to use on laying hens where the eggs are used for human consumption. For how long, as I didn't see a withdrawal time on the eggs, only meat? Thank you in advance for any assistance you can provide me.