Medical to work in Health Field on IEC

[sipfarms]

I have been approved for IEC & in the application I stated that I wanted to work in the health field (in the process of trying to complete nurse registration). There was no medical forms sent or notification that it was required. I tried unsuccessfully to get the medical before I lodged the application but the doctor wanted a number. I tried unsuccessfully again to email both the Australian & Canadian offices to get the form & it seems they can't change the conditions once it's been approved even though I said that I wanted to work in the health field.
I leave Australia next week & was wondering if anyone can tell me if I can change the conditions of my visa & get the medical once I actually get to Canada. If so, do I just go to the Immigration Office?
Any help would be appreciated.