It might be abscess
or a cyst
in my opinion.If it is red and warmth to touch hen there is chance of abscess and you need to apply neosporin
or anyother antibiotic cream over it.If it is acyst then clinical examination is needed by your doctor.Its always safe you take a second opinion
about this as your doctor may examine it and find the exact diagnosis.If needed they might also keep you in antibiotics for few days.Thank you.