My grand-daughter was staying over the week-end with her dad and I and she was menstruating. She is 9, her and this is her fourth period. She is over-weight and we were worried that this may happen. But, my question is, what are menstruation boils, and how and why does she have them too? There is about 6-8 of them on her inner thighs. Her mother told me that she use do get them, and that her mother told her that they are hereditary, that her mom (my grand-daughter's great-grandmother) also had them during menstruation. I have never seen them before or every heard about them. Please advise!

Concerned grandma....