Music keeps showing up that I do not want on my iphone

I am not sure what I did, but recently everything was fine with my iphone 5s and itunes in terms of when I would go to sync, but now when I look at "my music" on my iphone it has every song that I have ever purchased since I first got itunes, so needless to say it's a lot and annoying. But when I go to my music on itunes, I cannot find half the songs so I can't uncheck them. I have deleted a lot of them over the years but why would they be showing up on my iphone now? I tried deleting my music from my storage on my phone but it only deleted my playlists and not the songs in "my music" so I don't know how to get rid of those songs. Any help is greatly appreciated!