Hi, I would like to know more about the medication your vet gave your bird. The only antibiotic that I know of that will last more than a day is Doxycycline which will last seven days using the long lasting version.
A possibility from what you are describing and noted others is Giardia. If you bird did have Giardia it would need another type of antibiotic. Your vet can check for Giardia in a fecal float or Trichrome stain but the preferred method would be a PCR fecal test. Here is a link on Giardia: Giardia: Causes, Symptoms and Treatment Options as well as Prevention
All we can do is make suggestions, you vet with his hands on experience and diagnostic tool has to find the problem your little one is having.
gary
A possibility from what you are describing and noted others is Giardia. If you bird did have Giardia it would need another type of antibiotic. Your vet can check for Giardia in a fecal float or Trichrome stain but the preferred method would be a PCR fecal test. Here is a link on Giardia: Giardia: Causes, Symptoms and Treatment Options as well as Prevention
All we can do is make suggestions, you vet with his hands on experience and diagnostic tool has to find the problem your little one is having.
gary