Suggest Treatment For Open Wound And Red Bumps Below The Armpit

Hello Docotor, I have had an open wound just a bit below my armpit it heals, but not all the way. Then there is aslo a small red bump it the middle of the armpit. Sometimes it becomes hard, gets bigger, and hurts like a boil. After a while the appears to go away, but if i push the area where the bump was I can still feel it, but its only small. Also there are small pimples, they look like pimples, but black puss comes out. Please help me. . . What is this. . .