Why does my iPhone keep downloading songs from my iTunes account by itself?

I haven't synched my iPhone 5c to iTunes in months, but my iPhone has started downloading songs from my iTunes account to itself. I've deleted these songs from my phone several times and some I never added to my iPhone to begin with, but they keep showing up. I'm getting frustrated because they're taking up phone memory. I checked my settings and I don't see anything I need to change. I don't have automatic downloads selected for anything. My iPhone is up to date with the most recent update. Can someone help me figure out how to stop these songs from automatically downloading? Thanks!