Hi ! Good evening. I am Dr Shareef answering your query. From your history, it looks like a sebaceous cyst in your arm pit which gets infected secondarily with bacteria to give rise to signs of inflammation like pain, redness, etc. If I were your doctor, after confirming my diagnosis by a personal local clinical examination, I would refer you to a general surgeon for a possible excision biopsy for a confirmation of the diagnosis and a cure. Till then, you could go for a over the counter anti inflammatory drug along with a proton pump inhibitor for a symptomatic relief only. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing health care magic to clear doubts on your health problems. I wish you an early recovery. Dr Shareef.