Hi, I have three different spots on my skin - 2 in the armpit and 1 in the groin area - that are like pores filled with sebum. They get black heads and I can extract the sebum only to have it reappear. They are like a pore of winer except that the pore openings are connected under my skin. So when I extract, I get a long connected piece of waxy white stuff (sebum I guess) with black on each end where it was exposed. It's like a little tunnel under the skin. And they fill up enough that they raise the skin up until I extract and the skin flattens back down. They are not large, they are not red or irritated, they are just weird. What are they?