I'm having a wound in my armpit. What could this be?

I've had recurrent lumps under my armpit.. sometimes translating into an abscess. For the last month, I've been having pain under my right armpit with a seemingly tender spot. Having slight difficulties to lift my hand sometimes and while sleeping my index sometimes became numb. After one month, it became an external bump. Now it kind of fissured and is discharging small amounts of pus along a putrid / rotten smell with a very small protrusion of slightly bleeding body tissue. (Past 3 days)