My rat is sneezing. a respiratory infection?

my female rat had porphyrin on her nose so i thought i'd change the bedding into newspaper, but it hasnt work. she still has some and she sneezes a few times a hour maybe? i live in sydney AU and i want to check for a respiratory porblem for her, but how much would it cost? and if anyone knows any vets in sydney who handles rats well, it wwould be appreciated if i'd get their infos. thnx so much