My Daughter has a habit of sucking her finger and twirling her hair?

MY DAUGHTER HAS A HABIT OF SUCKING HER FINGER AND TWIRLING HER HAIR AND AS A RESULT OF THIS HABIT SHE HAS GOT A NICKEL SIZED SCAB ON HER HEAD THAT HAS BEEN THERE FOR ABOUT 2 YEARS,SHE IS 6 YEARS OLD AND I DON'T KNOW HOW TO BREAK HER OF THIS HABIT,I HAVE SHAVED HER HEAD THINKING THAT IT WOULD BREAK HER BUT AS SOON AS IT GREW BACK LONG ENOUGH SHE IS DOING IT AGAIN,CAN SOMEONE HELP ME WITH SOME ADVICE PLEASE THE DOCTOR SAID TO PUT LIQUID BANDAGE ON IT BUT THAT DOESN'T WORK EITHER.PLEASE ALL ADVICE WELCOME.