I would be pleased to answer your question .
She should surely avoid bursting the pimple or boil . It sounds like a recurrent folliculitis
. however since it is a Nipple , she should rule out any complications around the ducts or benign lumps or growths.
She should take an antibiotic course for a few days and a topical application of the antibiotic will help in treating the infection further .
Please do visit the Dermatologist
as early as possible.
Thanks and take care