I am curious if it might be an allergy. Did you change feeds recently? If not, I would try changing feeds to something with a different formulation.
Another thought is kefir - homemade, not store bought. Kefir is very much like yogurt, but contains beneficial yeasts as well as beneficial bacterias. A good homemade kefir contains something like 40-60 different strains of beneficial strains as opposed to 4 or 5 in most organic yogurts. The beneficial yeasts will compete with the nasty yeasts (fungus, bacteria, etc.) and after feeding the kefir for a while, should overwhelm the bad and restore a natural balance. Kefir is easily made on the countertop at home and once they try it, chickens love it! It is excellent for people and dogs, too.
Another thought is kefir - homemade, not store bought. Kefir is very much like yogurt, but contains beneficial yeasts as well as beneficial bacterias. A good homemade kefir contains something like 40-60 different strains of beneficial strains as opposed to 4 or 5 in most organic yogurts. The beneficial yeasts will compete with the nasty yeasts (fungus, bacteria, etc.) and after feeding the kefir for a while, should overwhelm the bad and restore a natural balance. Kefir is easily made on the countertop at home and once they try it, chickens love it! It is excellent for people and dogs, too.