He was acting fine, but I called the vet anyway. He said that he would probably be okay, but it wouldn't hurt to give him 3-4 tablespoons of hydrogen peroxide to make him throw it up.
We gave it to him with some warmed up chicken broth outside. After about 5-10 minutes outside, my dad suggested bringing him in and keeping an eye on him, since it was soaking wet and raining outside. Within 30-60 seconds of him being in, he threw up 3-4 times. I took him back out, and then out on the screen porch since he was acting fine. He started feeling sick again, and one of the door was partially open. He walked over, nosed the door open, ran out to the grass and threw up 3 more times. I'm so proud of him! He's acting fine now, though, and he threw up the aluminum, cupcake, and peroxide, so hopefully he'll be okay. Phew! Thanks for the vibes.