Sorry for scaring you, Crisgal, but I always to prefer to 'err on the side of caution'.
When I was in charge of first aid in a secondary school, I often had 'sick' (rather than 'injured') pupils referred to me. Over a dozen years I had quite a few with pains in their sides, which might have indicated appendicitis. I ensured that they were all checked out by a doctor (usually at the local A&E unit). Unsurprisingly, there were many 'false alarms' but, just once, it really was appendicitis.
Similarly, if a student complained of feeling faint or queasy, I always asked if they'd recently banged their head or neck. That resulted in quite a few kids being checked for possible concussion. Again, there were loads of false alarms but one boy, who had fallen of his bike a day earlier, really had fractured his skull.
Also, when someone said that they felt queasy, particularly if they'd got a headache, I looked for signs of meningitis (such as aversion to light or the distinctive rash). I still feel terrible about the fact that I was away on a course when a 14-year-old pupil was simply sent home by the deputy headmistress, after she had said that she felt really ill. She died of meningitis the following day.
So, even though I risk being called a 'scaremonger', I hope that you'll understand why I will always consider the worst possibilities.
Chris