Bubbly/foamy eye sounds like MG. MG is very contagious to other birds. Its easily passed from wild birds to your flock. Once a bird gets MG its always a carrier of it. Some birds have MG and dont show symptoms their whole life. How old are the 4 chicks? Im assuming they have been exposed to the birds that are showing symptoms?*update*
I think this is a respiratory infection. The first hen I posted about stopped breathing weird but now my other hen has bubbly eyes. I have 4 chicks, should I treat the whole flock with tiaguard? Even the chicks?