Awake all night crying for hours

LO is 18mo and has been awake crying for hours in the night. She goes down just fine for naps but nighttime sleep is another story. For weeks she’s been fighting sleep for the first half of the night after bedtime. She’ll sleep while being held but immediately cries when we put her in her crib.

Her typical sleep schedule is:

Wake up 6:45

Nap 9:30-11:15

Nap 2:45-4

Bedtime 8:15-8:30

Anytime she takes just one midday nap she’s up even longer in the night. Separation anxiety? Teething? 18mo regression? Help!