Hi,
I am from Sydney too (but not there at the moment!)
It sounds like a classic rib problem. I have seen loads of them.
If you want an experienced physio to assess it, I would recommend that you ring Barbara Hungerford on 02 9719 9114 - speak to the secretary to see who she recommends near where you live (where do you live?). They will tell you who they trust with the sort of problem that you have.
From your history, sounds like an anteriorly displaced rib. There are techniques available to sort that out - but Sydney Uni don't exactly teach them! However, I know that it works (Level 3b and Level 4 evidence) so don't be put off.
If you need anything, let me know. I will be back in June 07. Finishing my masters in Perth at the moment...don't like sydney uni for a musculoskeletal masters (or sports for that matter)!