$900 for a culture is insane! The most I paid was $100. Maybe even $200 max.
$900 is ridiculous. I suggest looking for a new vet.
I suggest stopping the baths. That's just extra unnecessary stress on him.
Nebulizers are good. Maybe try the F10 nebulizing treatment by BHP if you can't find a good vet for a reasonable culture. Its good for minor RI and it won't hurt to try. But I still encourage you to do a culture.
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