S.
Make sure her ears are ok, my son used to be the same way and it was a persistent ear infection. His pain got worse when laying down...that might explain why she will not want to go to bed and be left alone with her pain.
In any case, I would not leave her alone with her problem (no matter what it is), if she cries and wants you, she needs you anyway, right? I would just be there to comfort her and let her know she is not alone. I know it's hard, but it shall pass..good luck