First, not all medicated feeds are the same. Make sure yours has amprolium. Others are antibiotics (and cocci aren't bacteria).
Second, medicated feeds are coccidiostats - that means they're designed to help keep blooms of cocci away - not treat the illness. Coccidiocides are designed to kill large amounts of cocci and thus treat an illness. Sulmet and Corid are cocciocides, and that's what you need. Note - Corid has amprolium, too - but it's in a higher concentration designed to treat, not just hold back a bit.
You'll want to use that in their water for all these birds as labeled.
Also you'll need to help the good gut bacteria reestablish themselves. Use probiotics for that. They're not a medicine - they're living bacteria that, when fed to the chicken, establish colonies in the gut to help the bird digest food, secrete enzymes and vitamins, change the environment in the gut to ward off bad bacteria and also pathogens like cocci.
You can use actual probiotics from the feedstore (Probios, Fastrack, for horses and cattle), from the healthfood store (acidophilus, also found at grocers and the pharmacy), or just plain yogurt (make sure it says live cultures on the side). If you get to choose, pick a probiotic that also contains "B. bifidum" in it. If you go to the health food store, check out probiotics designed for women for yeast infections. That usually contains a good mix of bacteria. Which ever you choose, do during treatment* and for two weeks thereafter every other day. *If you ever treat with any ---mycin or ---cycline drugs, never use the yogurt during the treatment - it inactivates the antibiotics.
Fourth - do NOT use antibiotics unless you end up finding out that this bird for sure has a bacterial infection. I don't believe she does. That will often cause more gut problems than it ever solves unless there's a serious bacterial issue, like E. coli. So they're not yet necessary in this case.
Incidentally to break an old misconception, the droppings don't necessarily have to have blood in them to be coccidiosis. And droppings with blood in them aren't always coccidiosis - sometimes regular bacterial infections irritate the lining of the intestines and cloaca enough to cause bloodshed. The way I tell if it's cocci is to look for either a rusty color, a more mucous texture, a pudding like consistency throughout the droppings - not just one here and there, etc. Then if you see blood, you know there's an established problem.
Hope this helps to start.
