Hello. Thank you for writing to us at healthcaremagic I think the bump is most likely a sebaceous cyst which is collection of sebaceous contents in a cavity enclosed by a lining wall. The lining wall contains secreting sebaceous glands. It may become secondarily infected with bacteria and then may become painful and swollen. If I was the treating doctor I would suggest a course of an Oral antibiotics for a week to take care of the bacterial infection. My choice of Oral antibiotics would be either flucloxacillin Or cephalexin for a week. Once the infection subsides, the cyst is best removed surgically in entirety along with the cyst wall to prevent it from getting filled up again. I suggest that you visit a doctor in your region for a confirmatory diagnosis as well as appropriate treatment Regards