Have either of you added any new flock members recently? How old are your chickens. Have you looked up information for Coccidiosis? Coccidosis is a parasitic infection of the intestinal tract,it is spread by droppings which get into feed/water via droppings. Some symptoms of cocci are: runny/watery poop(may or may not contain blood,depends on which of the 11 strains it is)fluffed feathers,lethargic,not eating/drinking properly,weight loss,general look of unwell. If symptoms match,purchase Corid(amprolium) or may be called Amprol(amprolium). Dose for Corid/Amprol 9.6% liquid is 2 tsp per gallon of water,dose for Corid 20% powder is 1-1.5 tsp per gallon of water. Treat ALL birds for 5 days,make sure medicated water is the only water they have to drink. Treating birds with Amprolium for cocci will not harm them,but not treating if they have coccidiosis will result in deaths. Coccidiosis kills very fast. Older birds can have an overload/outbreak of coccidiosis.
Have birds been checked over for lice/mites? Worms can also cause similar symptoms,but if deaths have happened fast and within a couple of days of each other,start with coccidiosis as the possible cause.