That'd worry me because the blood's bright. Mine had Cocci in mid summer and roundworms a month later, and their poops looked like this both times.
The best thing to do is grab a sample and run it to a vet. Most vets will run a fecal test for $15-$30 even if you don't regularly go to that vet. If you want, call around to find the best price. Then all you have to do is run a baggy of the poo to them and wait 10 minutes for the results.
They can tell you what it is and exactly how to treat it so you don't waste valuable time & $$ trying to figure it out. Different worms require different medications, and they can tell you or give you exactly the right one to knock the problem out.
You could start dosing with Corid again in the meantime. Like @Wezdin says, coccidiosis is easy to catch, and if your flock had it before, you know it's in the soil. Cocci can also be freaky fast moving and Corid is low risk, so it's good to do that to keep anyone from getting worse (they can go from no symptoms to death in 24 hours).
However, if it's not coccidiosis, then the Corid is unnecessary, and it could cause vitamin deficiency and let the real problem get worse.
The new birdies just had a stressful journey to a new place, so their immune systems may be down enough to pick something up, or they could've brought something with them. Either way, you'll have to treat the whole flock for whatever it is or end up chasing whatever it is for way longer than necessary. Acting fast could save some birds. Good luck to you and the flock!
The best thing to do is grab a sample and run it to a vet. Most vets will run a fecal test for $15-$30 even if you don't regularly go to that vet. If you want, call around to find the best price. Then all you have to do is run a baggy of the poo to them and wait 10 minutes for the results.
They can tell you what it is and exactly how to treat it so you don't waste valuable time & $$ trying to figure it out. Different worms require different medications, and they can tell you or give you exactly the right one to knock the problem out.
You could start dosing with Corid again in the meantime. Like @Wezdin says, coccidiosis is easy to catch, and if your flock had it before, you know it's in the soil. Cocci can also be freaky fast moving and Corid is low risk, so it's good to do that to keep anyone from getting worse (they can go from no symptoms to death in 24 hours).
However, if it's not coccidiosis, then the Corid is unnecessary, and it could cause vitamin deficiency and let the real problem get worse.
The new birdies just had a stressful journey to a new place, so their immune systems may be down enough to pick something up, or they could've brought something with them. Either way, you'll have to treat the whole flock for whatever it is or end up chasing whatever it is for way longer than necessary. Acting fast could save some birds. Good luck to you and the flock!