R.R.
Mom of two boys here - ages 25 and 6 (yeah, that's not a typo - there are 2 girls between them). Anyway - the oldest has made more than a dozen ER trips, probably 8 or 10 sets of stitches. Youngest, only once for a very high fever. I used to be an EMT. With head injuries - immediately use ice. Put ice in a plastic bag, cover with a thin cloth or towel and hold it there. Try to keep it iced for 1/2 hour or so. You'd be surprised how much swelling that keeps away. Look at their eyes, make sure pupils are the same size. If they vomit, take them in right away (unless you can tell it was from crying). If they get really sleepy, and it's not bed time anyway, call the ER and ask. Sometimes they will have you wake a child once every hour or so after a head injury.