I would love to see a pic from last week's bird.
Standing around huddled and fluffed is a sign of illness. If it was truly bloody looking diarrhea, then Corid was the answer. But...if it is worm overload, which can weigh down young birds quickly to the point of anemia, Corid would do nothing.
Wazine is simply "off label" now meaning the FDA no longer approves its use in layers of eggs for human consumption. It was used with great success for years, although it only targets round worms, and if used without rotation with other wormers, can have resistance built against it by the worms.
The whole FDA approved stuff is merely politics and the woes of "natural" flooding the legislature from people who don't like drugs.
If you use the eggs only for your family, you can use off label. It gets trickier if you sell or give away eggs. No egg police goes around to small holders. It's only if you have 3,000 birds or more that you have to receive regular inspections which includes illegal residues.
Thus, if you use the off label wormers for your flock, you can decide what to use and how long to pull eggs, if any time, depending upon your egg uses. Many (most) of the wormers are also used for humans at much greater concentrations. Overall what residue remains in the egg is minuscule. The real fear is the over use of antibiotics as there is now thought that over use of food animal antibiotics, with antibiotic types used in humans, helps build the super bugs that become antibiotic resistant. And to their credit, there was a time span in farming where too many animals were crowded into too small an area and then relied on heavily medicated flocks and herds to deal with the subsequent illnesses. Fortunately, those days are mostly over.
Do be aware that if someone outside your family got sick from your eggs, and they were tested and illegal residue found, then you could be liable for any FDA sanctions that might arise. Hence the super long pull times so that NO residue can be found. Some pundits (usually vets) believe that you have to remove the bird from production if ever treated, while yet requiring treatment of any sick bird. Organic farmers like my daughter simply cull at that point, which is sad, because the animal becomes a huge liability.
THAT's why there are restrictions on antibiotics, and sadly a lot of the wormers were also restricted though they are not antibiotics. Many companies simply gave up with the expense of keeping up on all the extra studies required to prove safety under the new regulations. Small back yard keepers don't create a large enough market to warrant their expense of FDA approval. Large commercial operations use sanitation and swapping out the flock every 2 years...which means any animal over 2 years is generally culled...to eliminate any need to treat.
So if you suspect round worms, it is safe to use the Wazine on your birds. Follow label. If you have anyone in the family with drug or chemical sensitivities, pull eggs for about 2 weeks from the last worming ( Wazine is often used in several 2 week intervals). You generally worm, then worm again 10 to 14 days later to get the adult worms that have now hatched.
But that assumes worms (and only round worms if Wazine is used). If it is truly coccidiosis, then Corid is the answer.
Only a fecal float and sample at a vet would know the true difference. Barring that (as many can't find a vet that treats chickens or don't wish to spend a lot of dollars on a chicken), then you have to go by symptoms with some hopefully educated guessing.
LofMc