Q: iPhone 6s deleted non purchased music

I've had my iPhone 6s since about October without any issues. I listen to my music every single day through my aux cable in my car, and yesterday, all of my music was gray, and said I couldn't listen to my music without it being connected to wifi. Then once I continued to scroll down, I noticed that any music I had gotten from CD's or downloads was completely erased.

I haven't changed any of my settings to make this happen, and I haven't hooked up to iTunes in weeks, so I have absolutely no idea how this could've happened. Has anybody else had this issue? I'm scared to sync it to iTunes now because I don't want anything to get permanently deleted, and I was hoping to keep restoring to a backup as my last resort, as I'm sure my most recent backup is still a few weeks old.