He may have had an upset stomach or teeth moving under the gums, or pressure on his ears.
TBH there will be a reason, just pretty hard to work out when they aren't very verbal.
First, why they call it terrible two if it's starts sooner than two??? Argh
Terrible twos are a bit different from a night time upset & even though it went on for 2 hours I'd not call it a tantrum, a tantrum is more about something like them not being able to wear shorts on a cold day etc, I do think if they fall asleep independently etc then there could be lots of reasons, like a sudden noise waking them & them being frightened of it.
Also some medications are best not given on an empty stomach & I know with my DS1 we had a horror night after giving medication for pain & him being up half the night... I've never used Tylenol, but I'm pretty sure it's not the best on an empty stomach, so that could be a big part of the problem & it was the upset stomach that kept him upset.