Start with treating them for cocci.hhmmm I am now wondering if water is an issue here. My hubby and I were gone for a week and our daughter was caring for them, Im thinking its doubtful that the water was changed every day :-(
Get 20% corid powder and give it to them in water: 1.5tsp per gallon for 5 days. Make a fresh batch each day. After the first treatment course, give them 3/4tsp per gallon for another 5 days--this helps the chickens build up resistance.
Give them b vitamins after the two treatments.
Best!