Well, I think it might be yellow fungus, which a fatal disease, but I'm not sure. You're going to need a biopsy to make sure, not a culture. A biopsy means they take tiny bits and then those bits are cultured for different fungi. So that's what you need to do. If your vet says bacterial insist on a biopsy first. When Titan showed that kind of thing, my vet thought it was bacterial because when I got him from the pet shop, where he'd been abandoned, his left side of his face had been burned. So we put him on antibiotics and it got worse, that's when I got the biopsy done. So please get that done first, it's expensive but worth it. If it comes back as yellow fungus, contact me right away, I'll tell you what meds to take and how to take care of your little one, k? Titan did pass away, poor sweetie. I'm hoping it's not yellow fungus, though.
Good luck, keep me updated, k? Don't even have your little one take any meds, even if he has parasties from the poop, until the biopsy comes back, k?
If I'd know what I know now, maybe Titan would have lived longer.