Was she removed for an injury or was she just substituted for?
In tournament play, a player removed by injury or illness needs a doctor/ medical personnel approval to continue in the game.
Actually the rule just says the doctor or medical person gets the final say. IOW they can stop you from re-entering a player but they don't need to grant permission.
Example: Player scrapes an elbow. Coach washes it off and puts a band-aid on it. He does not need to ask permission to re-enter the player, however, if the medic thinks he should not go back in the re-entry can be stopped.