The cut is on his right side, right in the middle (before the beginning of his back leg). I removed one wooden stick from there that I thought might've been the culprit.
They gave him pain meds (it's a liquid opiate, 0.25mg or less per dose), and I'm glad because now he seems a bit calmer. I asked him if he should be on antibiotics and they said no, it's not infected, and told me just to watch for signs of pus. :\
I've been cleaning the cut throughout the day with the sterile solution they gave me, and it's finally scabbing again. I'm praying he doesn't fuss with it.