I'd do an extended course of treatment just to make sure you kill off the parasite.
As far as the temperature, reduce the heat - the heat plate alone is enough, they don't need the rest of the brooder kept so hot.
Very hard to see but it looks a bit bloody. Any reason you only did 5 days of Corid instead of the full course of treatment, if you're suspecting coccidiosis? https://www.backyardchickens.com/articles/treating-coccidiosis-with-corid-amprol-ampromed-the-correct-amprolium-dose.73341/
As far as...