Why doesn't the music app work anymore?

I recently updated my iPod touch 5th gen to iOS 8.4, upgrading to iOS 8 was a mistake in the first place, so, if you haven't updated yet don't! As you all know you get the new music app with the update, unfortunately, the music app is now almost completely unresponsive, and when it responds doesn't load some of my music and when you click on an artist, it just says 'loading' forever... I've tried restoring it from a .ipsw file in iTunes, but, it then says it can't be registered with apple.

Basically, I'm asking is there a way to get it back to iOS 8.3? or even better iOS 7, the iPod struggles with even typing at this point, and no, getting a new iPod isn't an option.

Many thanks.