Who's Bleeding?

OK, so there have been strange tiny blood droplets outside on the sidewalk and then today in our hallway (thank goodness it's hard tile that cleans oh so easily.) I have inspected every child, dog, cat, and rodent (well, no, not really), but most of the rest and no trace of injury or bloody nose or any other...uh...part. It is common to have bleeding injuries here with four children and a part of our DNA hard-wired for clumsiness (it's the Scottish, I'm convinced of it), but this remains a mystery...