Girls, please tell me, a child near the anus has a sore like a pimple …

Girls, please tell me, a child near the anus has a sore like a pimple at the beginning, it was just raised and now it's white. The baby is not bothered, behaves as usual, stool is normal. What could this be and why? We will go to the pediatrician only next week, so I want to know from you first.