I have a 1 year old. She's had 3 rounds of prescription anti biotics and she eats fermented food.
Most of us more experienced folks refer to coccidia and coccidiosis in their correct context as often as possible for exactly the reason you note.. Cocci.. is a very shortened and misused term. After 3 round of antibiotics.. I'd start to worry about MRSA etc.. but now one else in the flock is having issues? Has she been separated or can you describe things in more detail please, good job already.
Try stopping the fermented feed.. since it clearly isn't helping anything. How long have you been doing this for?
Standard moistening the feed gives almost the same benefit.. IMO.. And FF didn't save me a dime, increase the health of my flock, or any of the other things touted by it really.. See if my link works at the bottom, it's a good read but keeps downloading to my chrome book instead of letting me link it.
What is this feed that you ferment? Is it a formulated ration?
What are the symptoms of her bacterial over growth please? Is she a recent addition? How many birds in how much space? Waterer type? Any previous unexplained death or limping? Ever treat for coccidiosis as a chick? Were they vaccinated for Marek's?
Gram positive cocci are staph and strep.. virtually in every environment.. YOUR gal is having a personal immune system condition.. try and boost her immune system if battling the bacteria isn't working.. add in significant probiotics instead of relying on FF.. Add in some B complex!
Get something like rooster booster BRAND
Poultry cell product or
Poultry Booster
Please understand that I'm here to support you and your flock and all my questions are just looking for clues to that end. I don't have all the answers, but I do think you are asking some good questions.. that I can surely also learn from. Sorry you face this. It's obvious you are working very hard to resolve it and care about your birds! Thank you for sharing your challenge with us! I hope you do get some answers and that she recovers quickly!
Some key resources of knowledge here, appreciated by many..
@ChickenCanoe @Eggcessive @Wyorp Rock, TIA ALWAYS!