May I ask if you think I should be doing a third round of Corid?
Hi, it takes a long time for chickens to come back from coccidiosis. Do not expect big results overnight. Keep her high on proteins and low on calcium if she does not lay eggs which is probably unlikely now. (no layer feed for now) If you notice bright green diarrhea turning darker and hopefully turning brownish she is on the right track. If coccidia is gone she needs time to "rebuild" her guts. But coccidia is probably in the ground (earth worms carry coccidia oocysts for an example) then preventive Corrid 3-4 times a year at lower doses is probably needed. Separation of poop away from feed/water is very crucial. Oocysts can stay active in the ground for 8 months. She needs time, no wild foods, just easily-digestible feed. Emeraid Omnivore Intensive Care works magic but a prescription from a vet is required and it is super expensive - roughly $50 a pound. Worth every penny though.
If you did 2 rounds of Corrid the right way - 5-7 days of treatment, 9 days gap and then another 5-7 days of treatment that should be enough but if you missed any of these steps then you might want to repeat.
Other parasites might also be present and Corrid will not eliminate them but that is another issue. If you see signs of progress just keep her for now on grower feed (soaked feed cant be used for too long, no more than one day) and warm.
May I ask if you think I should be doing a third round of Corid?
Do you see progress - is the watery, bright green diarrhea turning drier and darker ? Do not expect much progress overnight , just very small changes must be observed and analyzed. It takes a long time for a chicken to come back from coccidiosis. Damage to intestines does not heal easily. I would keep her only on grower feed and water. Weak chicken needs balanced diet of many nutrients. Grower feed is a very balanced feed containing many necessary supplements that some foods in isolation can not provide. If her poop improves then you might slowly introduce different feed. You have to judge from observations whether the chicken improves and whether another dose of Corrid should be given. Remember that Corrid is only effective against adult coccidia. It does not do anything to the "larvae" buried in the guts. You have to wait for them to emerge as adults and then finish them up with amplorium. The 9-day gap between treatments is to allow coccidia to mature and be finished with amplorium to break the reproduction cycle.
Coccidia is probably in the environment where you are and preventive treatments with Corrid are probably necessary to be repeated 3-4 times a year. Keep in mind that chickens mask their health problems very well until it is so advanced that they cant hide it anymore. Coccidia oocysts are very tough and they survive in the ground for even 8 months so reinfection is very probable.
Keep your chicken warm and on a clean, dry bedding. Since she has diarrhea you could use old blanket, towel covered on top with paper towels which would absorb the moisture and can be easily replaced when soiled. Straw, hay etc. is not recommended because she would probably eat some and will not be able to digest it. That would lead to crop issues. That is nice you took her home. Not too many people would do this, unfortunately. Let me know.