Rhorer says it was unusual for a mother to inject a child with the anti-wrinkle shot.
Campbell appeared with her daughter Thursday on ABC's "Good Morning America." She enrolls Britney in beauty pageants and says she got the idea to give her daughter Botox from other pageant mothers.
Rhorer says his office received numerous calls from people concerned about Britney's well-being after the TV appearance.
Botox injections can be painful and are not recommended for anyone under the age of 18.