S.H.
She is sick.
She is teething.
She is uncomfortable.
She has all of these things, at the SAME time.
That... would make even an Adult, fussy and uncomfortable and not able to sleep well.
Plus, she is on the cusp of 18 months old. When on the cusp of an age change & growth-spurt... babies/kids, get tweaked. Because, they are changing so much at these junctures both physically and cognitively and even their appetites increases at growth-spurts.
So, all of these things, really tweak a child.
It is often, many things at the same time, that affect a child and then their sleep. It being growing pains and temporary tweaks.
Also occurring at this age, is "Night Terrors." Look it up online.
This is normal and is a developmental thing.
She has MANY things, going on at the same time. But a baby/child, cannot just cope with it, so well. Its hard on them. Thus it affects their sleep, too. Because, they do not have coping-skills nor deductive reasoning, like Adults do.
Ear infections don't always produce a fever.
If anything, take her to the Doc to check for that. So that you can rule that out or not.