The bump might be a infected Lymphoma
or a infected sebaceous gland
To get rid from this problem you have to take a course of antibiotic and than if need excision or drainage
of the bump. But about 90% of the cases cured with the antibiotic only.
Consult you doctor as soon as possible and get started you treatment. For pain you may use any analgesic
and anti-inflammatory drugs.
Hope this will help you.
Best Wishes and get well soon