Great news, I know your so relieved. Might be a good idea to keep her in till she is stronger. giving her extra time to completely recover is good especially with all the TLC and extra vits. As far as an extra day of meds, go with what you feel is best. Hoping ya'lls weather takes a turn down...
I have heard that in some parts of the country it is in the soil and hard to get rid of, Are you giving her some kind of electrolytes or vits in her water , I think I would . I don't know if wild birds bring it in or not, but wild birds are every where so I don't know how we would be able to...
I'm sorry about your duck, I have never had a duck or chicken for that matter to have cocci, so i can't help other than to say I hope she pulls through, you may want to give her till the weekend is over then decide it just may take her a little longer to bounce back. Unless she just continues...