I am so glad you have a diagnosis now, @CurlyCurly - and I hope the antibiotics kick in soon & the breathlessness stops asap. xx Surprised that didn't show on the xray! Might be worth getting it 're-read' by an independent radiologist!!
(hmmm ... Tho I had my mammogram 're-read' by BreastScreen NSW after they missed my BC - and they STILL missed it, 2nd time around! grrr)
Re a specialist diagnostician - we were lucky to have one locally (but he has recently retired) and a school mate of my husband's was also one (also recently retired.) They are also called "General Physicians - your GP should be aware of any locally .....
General physicians are consultants who care for patients with special or difficult problems. General physicians only see patients who are referred to them by other doctors, usually by the patient's own general practitioner.
https://www.imsanz.org.au/about-us/what-is-a-general-physician