Playing random artists when I am listening to ONE artist album

[champagnelana]

I have the iPhone 6s with IOS 10.2 my Spotify is updated to the most recent version but when I am playing one artist album it will start playing different random artists songs instead of staying in the correct album. I have the free Spotify account but this still should not be happening with playback. For example:
I was playing Florida Georgia Line's "Dig your roots" album and a song by Nelly started playing in the middle of it.