Fellow physics to med here. I have a B.Sc. in physics and will be starting at Ottawa this Fall.
You definitely do not need any health-related EC's to be a successful applicant. The first thing you should do is take a look at how all the schools calculate your weighted GPA (e.g., UofT drops lowest marks based on full-time course loads, Ottawa weighs later years more heavily, McMaster just takes your raw cGPA, etc.). Once you take your MCAT, you'll have a better idea of where you stand. Focus on CARS so you raise your chances at Mac.
The importance of ECs can get overblown for Ontario schools. I consider myself as someone with average ECs. I only had around 16 items on my ABS sketch for OMSAS and I managed to get 3 interviews in Ontario this cycle. Taken altogether for Ontario, GPA, MCAT and CASPer are each way more important than ECs. You definitely do not need any health-related ECs to be successful here.
Lastly, don't underestimate the role that CASPer plays. some people say that "you can't prepare for CASPer" but that's untrue. I took the CASPer test over 3 times because of rejections in previous cycles. My first attempt at it was complete rubbish, and over the cycles I got way better. So the MCAT and CASPer are the things that give you the most bang for your buck (in terms of time spent on them vs. positive effect they have on your application) in Ontario and lots of other schools as an out-of-province applicant.
So calculate your weighted GPA at each school to get a better idea of your chances. Do great on the MCAT (especially CARS) and CASPer, write awesome essays based on your unique experiences, and you'll have great odds.