Did you notice a really bad odor from the chick with swollen eyes that you put down? That can be a sign of coryza. MG or mycoplasma gallisepticum can cause milder symptoms, but may cause swollen eyes with bubbly eye drainage. Sneezing sounds more like infectious bronchitis or MG, but hard to know without some testing. Have you tried to contact the seller? Have your grown hens every had any type of respiratory infection? MG, IB,and coryza can show up within 2-3 days of exposure. If another shows symptoms, I would cull it, refrigerate the body, and get a necropsy by your state vet to identify the disease. MG and coryza cause chickens to be lifelong carriers. IB does for up to a year. MG can be passed through hatching eggs. Sulfa antibiotics are only available from a vet nowadays. Tylan 50 injectable, given orally to chicks, can help treat symptoms in MG. MG is very common in backyard flocks, but most people close their flocks to new birds when it affects their flocks. Culling any very sick birds is wise. Most people recommend keeping new chickens quarantined for at least 30 days, just to look for signs of illnesses like these. Sorry that you are dealing with this.
