<human>: Hi, yesterday I noticed a painful lump on the inside of my upper arm. It is painful and I know I did not injure it. It is not bruised. It is about the size of a jelly bean and my arm hurts when I use it. It came on so suddenly that I am wondering what caused it. Is this normal?
<bot>: Hi. Thanks for your query. Noted your history of sudden pain and swelling in the inner part of upper arm, occurred without any obvious injury, is of the size of a jelly bean, and the pain increase on using the arm. The most probable cause in such a case is a small abscess from a boil. There would also be redness and local tenderness. I would advise you to consult a Doctor as you need a clinical evaluation, examination and most important the prescription for an antibiotic and anti-inflammatory and painkiller medicines.