Sounds like CRD. Caused by MG. Watch their eyes. Makes sure they don't get goey and close shut. Watch for a white solid mass to form and make sure you get it out of their eyes. Put bleach in the water to keep it from spreading. Recommend not breeding them. Breed for resistance. I stopped medicating because I got tired of treating sick birds all the time. Started culling sick birds and only breeding ones that never showed signs. Between that and not trying to raise chicks thru the winter, I rarely get a bird with CRD now.
God Bless,