I haven't gone through anything similar as I have no children, but even though you are unsure it happened and unsure it may have effected your daughter, I would take her to a therapist for children and might even report it to the police. The other child admitted it, whether truth or not, there needs to be some sort of investigation to get to the bottom of it.

I seriously hope that nothing happened to your daughter. Things may seem fine on the surface, but you never know what may be brewing. If you get her help now (assuming it really happened) then she can work through it.

I still remember things from when I was 3, so it isn't too young to have memories.

IDK, Hope that helps a little?!

BJ