Hi my husband keeps getting these bumps under his arms. He popped one because he thought it was a pimple. It went away in a couple days but spread a little lower and on his other arm pit. Those went away after a week but, they came back yesterday. They are not on his arm pit exactly but a little lower. We are concerned what is this. Where do they come from and how can we get rid of them for good? Please help! Thank you