Turns out I didn't need a doctor's care, just lots of thorough cleaning and airing. Which is good, since I didn't really want to see a doctor; I would have felt silly!
So what was that all about anyway? I have a theory, of course. I figure that perhaps I did have a tiny bellybutton-sized alien baby, and all that ick I experienced last week was the remains of its emergence. If this is true, it means my alien child is out running around among us. So if you see a tiny alien baby, please tell her to come home, as it is past her bedtime.