Interesting, I didn't notice that. I wrote it as 4 lines each, and I was thinking about removing the line breaks to make it so:
1
2
3
4
1
2
3
4
etc.
But the portion you mentioned is 5 lines, so if I did it that way, it wouldn't exist.
And now that you point it out, I really like it too!
If you check my poems, I tend to have the last stanza break the format, whether by having it be an extra line, having a separated line, or introducing rhyming after not doing it in the other sections.
I think the ending should stick, and making it stand out by rules-breaking in it helps you do so.
You're still missing a line somewhere to end up with 4-4-5 though. Might be worth going for it. I'd put it just before the first "It hurts," as the final line in the second stanza.