Does your daughter, when she's sleeping, have her head turned to either side...and then perhaps some "drool" may accumulate on her bedding right there, and being that it is "damp" because of it, it may cause some skin rash/problem there?
Or if she has a sippy cup/bottle in bed with her, or sucking on a pacifier... saliva may "drool" & dribble to the side of her face in which she is turned, and thereby making her bedding damp right there and making her skin irritated, where her ears happen to be?
My son is a sweaty type, and sometimes wakes up with the side of his face/ear area sorta sweaty right there on the side of his face, where via gravity would then make it damp on his pillow.
Just an idea.
All the best,
Susan