Thanks for the query,
She might be suffering from furuncle
It is a deep bacterial infection.
Give her a course of antibiotics.
An X ray
is also required,
Sometimes jaw tumors present in similar form.
X ray can be helpful in ruling out this.
Please meet a dentist
for exact diagnosis.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
Wishing you a good health.