My budgie has AGY - advice appreciated
Hello everyone. First I would like to apologize for my long absence, a lot has happened in my life this past year, and I am also very sorry for this long wall of text I'm about to write. Last time I posted, it was about my budgie Akira, who sadly died after a short battle against what I first thought to be psittacosis, but now think might have been AGY. He left behind his companion Sue, who joined him shortly after, just as unexpectedly. Right before Sue's passing, I had bought her another budgie companion, Stan, since I hated the thought of her being alone. When Sue died, I was devastated and decided to keep Stan as an only budgie. He bonded with me quickly, and I love him so much. I've been terrified that he'd meet the same fate as Sue and Akira, and a few days ago, I found out that he not only has AGY, which I've feared for months, but also internal parasites. As you can imagine, I was very upset. I can't stop thinking about the worst possible outcome. So I would like some help and advice, if you can.
Stan now takes the medicine Megabac, which I put in his water. Is Megabac usually effective against AGY? I read that Megabac is not good for them, which made me very worried. I read something on here about sodium benzoate, and somewhere else, I read that thyme and apple cider vinegar also help. I'm getting a bit panicked thinking about everything that might happen, so I'll end this here now and might add other things later.
Please, if you have any helpful advice - anything that the vets might have forgotten to mention - I would greatly appreciate it. I just want him to recover. Thank you.