Yo fargo,
In all likelihood, you accidentally laid hold of a polychaete "bristle" worm while handling the rock.
The "chaete" in "polychaete" refers to the the bristles or spines that these worms arm themselves with, and can contain certain amounts of irritating toxin. The often barbed spines are mostly proteinaceous, so dipping in vinegar won't dissolve them.
Tweezer time, I'm afraid.
Some swelling is normal, but if it gets out of hand and a fever develops, see a doctor.
I myself have been porcupined by glass sponges, funky-looking chitons, and the odd sea urchin: Welcome to the club!
from the pincushion of the reefing world,
horge