Background checks that employers do are typically to make sure you are who you say you are and that you don't have a criminal background (and in some cases, your credit score can be checked). If they verify employment history, it would be by contacting your previous employers that you put down on your resume. As far as I know, there's no database regular employers can go into to see where exactly you worked at before. I mean, how intrusive would that be? And even if there was, you're not actually an employee for any cam or clip sites. You'd be an independent contractor and get a 1099-MISC form when it came time to file taxes. So, even if they could look into your tax history, which they wouldn't, your tiddie streamer money would be seen as miscellaneous income. So, you're good on the background check front. Granted, all this info is based off how it is in the US, but I doubt it's much different in Canada.
However, you do need to consider that you're probably going to have to sign a morality clause when you get hired as a nurse (again, this is based on the US, so it could be different in Canada). With that clause in your employment contract, if your employers do find out about your camming past, they could fire you for "unprofessional conduct". It's pretty messed up, especially since camming and porn is totally legal, but it's unfortunately how the world is.