The second (or first) experience happened in early 2020.  I'm not sure when it started, but it culminated in mid February.  On any normal day, when my brain isn't forced to do other things, it's making up a story.  But at this time, instead of my usual story-making, I kept hearing hymns in my head. It went on for days, and then more than a week. Hymn after hymn during my idle times.  Some of them were even hymns I didn't particularly like, though the lyrics were always limited by my own memory o