When P had pneumonia in May it was dignosed through her chest x-ray. Her chest sounded clear but the x-ray showed it wasn't.
Symptoms were cold symptoms, high temp and very lethargic & unhappy. I thought she had tonsilitis but they were clear. That's when the GP ordered the x-ray just to be sure. The radiographer sent her straight back to the GP, who sent her to hospital.
You can always ask the GP for referral for an x-ray. If you have it privately you can just walk in and get it done. You might be out of pocket some $$ though, but I thought it was well worth it.