K.G.
This happened to me and my husband with our first child. As soon as she was in a "big girl bed" she was up and down 6 or more times per night. It was terrible and seemingly lasted forever because we too were exhausted. Our pediatrician told us to lock her in her room, we were never comfortable with that but a pediatric nurse practitioner suggested we put her crib mattress on the floor at the foot of our bed and if she gets up have her lay down on that and gradually move it closer to her bed. The point for us was not letting her get in bed with us. It worked for us and shortly the sleepless nights were over.