I have a small backyard flock of just 11 birds, and in the past month we've dealt with scaley leg mites, lice, sinus infections, cankers, and yeast infections.. Everything kind of hit us at once. Natural treatments did nothing so my poor birds have had a whammy of wormer, antibiotics, antifungals, etc.. They are free range birds that get tons of greens, bugs, and fruit (we have a small orchard and they eat all the fallen fruit), plus they eat organic feed and seeds, and all our healthy food scraps. I give them lots of probiotics. I keep their coop very clean. They have a dust bath with DE and clay that they use regularly. They are happy birds. We have just had some bad luck and I hope to prevent anything else from happening. I bought a vitamin supplement today and have VetRx on order. Are there any 'magical' immune boosters I can give them? Also I'm still dealing with cankers on two of them... One has them in her throat and she is starting to have a rough time. They have copper sulfate and apple cider vinegar in their water and are taking metronidazole. Is there anything else that will help? Thanks in advance.