If you have coccidiosis or Marek's, I think you'd have more hens with the same symptoms. I found a good article on coccidiosis that may help you. Here are some sections of it and the link to the whole thing:
http://attra.ncat.org/attra-pub/PDF/coccidiosis.pdf
Outward signs of coccidiosis in chickens include droopiness and listlessness, loss of appetite, loss of yellow color in shanks, pale combs and wattles, ruffled, unthrifty feathers, huddling or acting chilled, blood or mucus in the feces, diarrhea, dehydration, and even death. Other signs include poor feed digestion, poor weight gain, and poor feed efficiency. Some symptoms can be confused with other diseases. For example, necrotic enteritis is a gut disease that also causes bloody diarrhea.
If signs of the disease appear, use drugs that are appropriate for coccidias late life cycleonly sulfonamides and amprolium. (Reid, 1990) When birds are getting sick, they lose their appetite. Therefore, soluble medication should be provided in the drinking water.
Amprolium is an anticoccidial drug. It has also been used for many years and needs no withdrawal time to guard against residue in the meat. It is given in the drinking water and interferes with metabolism of the vitamin thiamin (vitamin B1) in coccidia. Amprolium treats both intestinal and cecal coccidia.
Small-scale producers can control coccidiosis with a good understanding of its life cycle and conditions for transmission, by management strategies such as good litter and pasture rotation, and by using drugs only for rescue, if needed. Large-scale producers, especially organic producers, increasingly rely on vaccines.