D.K.
I would check for reflux with your Dr which can be painful while laying down position. Your Dr can evaluate her symptoms. Though it would be ongoing pain every night and naptime.
Otherwise I am betting teething, they hurt, especially at night, some worse then others.
Try giving her mylicon for gas relief, is she pulling her legs upwards to her chest (sign of gas pain)
Try motrin before bedtime or teething tablets, see if that helps her. Is she slobbering a lot, red gums, biting down hard on things?
She is also going through possible seperation anxiety, learning that she is to be away from you when going to sleep. Reassuring her on this but not picking her up immediately will help her. If it is this it will be a phase that will pass and come around again!
I never did have to do crying it out much with my kids but did it in 10 minutes at a time as they got close to one.
I would give them a chance to calm themselves, if they didn't I would go in, put on music and rub their backs but not putting them to sleep but not picking them up either unless they were truly afraid or sick.