It's an elementary school nurse's office and they have kids going in and out all day with skinned knees, sore throats, nosebleeds, nausea, lost teeth, etc. It's not unusual for one nurse to be attending 2 or 3 kids at once. The vast majority of school nurse's offices aren't going to do an online look-up for every healthy child who presents to the nurse's office, nor should they be expected to.
The expectation should be for a school to actually have a registered nurse full time (shocking how many don't), and that injuries that could potentially be more serious than they look (head bumps, sprains, etc.) should be reported to parents via a phone call.
The couple of posters on this thread who have suggested, "Contact the school and tell them that they have to do X whenever your child visits the nurse", are suggesting that the OP should act entitled to special treatment. The nurse's office knows which students are medically fragile and need special care. That care shouldn't be diverted to spend extra time on healthy students whose parents' egos just need extra care.