Having read a fascinating book, possibly called How to Raise a Healthy Child - in spite of your doctor, by a medical doctor, I learned some important things about temperatures, and fevers.
1. Accuracy is over-rated -- if the child has a fever, it's obvious, and symptoms like listlessness and not being 'themselves' are far more important for diagnosis of critical illness than the number. In fact, seriously dangerous illness may have a fever of only 101, and 104.5 may be quite a mild ailment. Trust your instincts, not the numbers. At one level, temperature is measured in numbers because medical professionals like to have concrete things they can write down: not because it's a particularly important piece of information.
2. Fever is the body's natural response to invasion, and it is a healthy response. Treating fevers for mild ailments is much more likely to create protracted illness with bad side effects, whereas making sure the child is comfortable, hydrated and fed (if hungry) will support the body's pyretic system in doing its job: killing the virus or bacteria by overheating it.
3. Fever (or febrile) seizures are safe. The sudden increase in body temperature may sometimes bring on frightening seizures, but these are not associated with any other seizure disease (not even epilepsy), or any side effects beyond freaking parents out (and sometimes doctors).
4. Under-arm temperature is as accurate as rectal, ear, or oral (supposing you can get the child to keep its mouth closed!) if you add 2 degrees Farenheit to the reading.
5. Body temperature is both personal, and variable. Throughout the day, temperature varies as much as 4 degrees, so an increasing temperature toward the evening is normal, not a symptom of illness -- and should not be treated by any means. Additionally, just like 'normal' pulse rate being 72 has nothing to do with, say, me (mine's 'normal' at 58 -- a considerable difference!) the 'normal' body temperature may happen only very briefly in passing in ANY human body.
6. 98.6 is not 'normal' body temperature... it is an inaccurate conversion of 'normal' 37.3 Centigrade which for some reason got rounded down, then converted. 'Normal' is over 99 -- supposing that 'normal' has anything to do with your child.
So, when my kids were ill, I did the old, accurate 'hand on forehead then cheek' thing that demonstrates that, yes, their body temperature was up. Then I did what I always did with a sick child -- offered lots of fluids and camped out at home until it passed. I noticed that a high fever was associated with terribly bad breath (we called it 'breathing fire') and pale faces with bright red circles on their cheeks. If they were seriously ill, they also looked greenish or orangy around their mouth or eyes.
The book (whatever it was called) also alerted me to the risks in giving antibiotics often, particularly when they wouldn't work anyhow (viruses aren't damaged by them, only bacteria are), so I always insisted on a swab to ensure that we were only using them when it was actually going to make a difference.