Parakeet prescribed antibiotic pooping whole seeds?

Hello,
I recently took my parakeet to be checked out because she was sleepy/not acting herself and walked out with an antibiotic(amoxicillin). the vet didnt really seem to know what she was doing but all the avian vets in my area are booked solid. After a week of the antibiotics by parakeet is showing signs of improvement but now has whole millet seeds in her poop? The vet hasnt really given me direction of what is best to do next, and ive called other vets in the area asking for there opinion but im not getting any answers.
I found a fourm suggesting perhaps the antibiotics are now giving her a yeast infection causing her to have seeds in her poop and found a probiotic for birds i may try, but any advice would be appreciated because i really dont know what to do next.