I am not a doctor or vet, however, I have many animals and have to take care of them due to costs. Metrodiazinole is an anti fungal medicine and is also given to dogs when they have parvo. It could be that the vet is treating cocci, as it is also used for that in the canine world. Keep her warm...
The 2 redish colored are possibly Buff orpingtons or Red Sexlinks, the barred might possibly be Barred Rocks, the whites not sure, since they have yellow earlobes and waddles...could be white rocks, or some other white egg layer.
we talk to our hens all the time...I sometimes have to threaten them when they slow down in laying...of course I am only kidding when I tell them "if there are no eggs by morning, its chicken soup for dinner" amazingly, there will be one or two eggs by morning! lol