Presage

[Semicircle]

I didn't listen to the song, but I read that this guy based his act on the movie version of The Shining, which is something of interest to me.
And that he was writing about memory loss and the deterioration of the brain. Is this what the poem is alluding too?

Why didn't I listen to the song? That's a whole nother conversation.

You are correct.

I haven't watched the shining yet but you are spot on with your guess.