My amost 4 years old, born Oct 28, 2016 is sucking her two fingers especially at night. This is causing injury to her fingers and may affect her teeth. I can't get her to stop. She does it to soothe herself especially at night when sleeping and when she's upset. Her cousin did this till age 10 or so needed major dental surgery.. to the extent of breaking his jaw. How do i get her to stop?