iTunes credit and Country/Region problems

I just got an iTunes card today, so I decided to get some music. I tried to download it, then it said I could not Download it on the U.S. version (because I live in Canada, not sure why it changed the region.) so I tried to change the Country/Region, then it said I couldn't until I used my store credit, but I couldn't because I’m in Canada, I need to be in the U.S. to download stuff, and I looked all over this website trying to find something to help. I came up with nothing.