Okay, so I walked into the closet where Nathaniel was growling at Sophie about something, tried to figure out what he was chewing on, chased him around the apartment, only for him to swallow it. I walked back into the closet and on the floor was a torn up Tylenol cold medicine package. I think he only ate one, but I'm a little worried. He seems perfectly fine, and it's been about 10 minutes since he ate it.
PS I was transferring my meds from one location to another and the one little thing must have slipped out of my hands. I've thoroughly checked the apartment now to make sure that nothing else escaped, including under the bed.