Yes, all the signs of coccidiosis. Corid needs to be given for five days at two teaspoons of liquid concentrate to one gallon of water, mixed fresh daily. Then wait a week and do it again for another five days.
Do not stop the sulfa. This is the best drug to treat the inflammation of the intestines that bacteria causes that often moves in with the coccidia. It destroys the lining of the intestines and causes bleeding.
This particular bacteria is extremely intense and destroys a chicken very quickly. Yes, there is a chance your Polish will recover, but the odds at this stage are not good, sadly.
I would keep all of them on the sulfa for at least seven days or until the blood quits showing up in the poops.
Please tell us where you live. I'm betting it's somewhere warm and humid and rainy. Where you live tells us a lot when we try to guess what's making chickens sick. Climate factors into health in a big way.