I had it for years but it used to be too small so i didnt pay attention thinking it was an ingrown hair. Before, normal pimple in size, movable, spherical, and it has two little openings that expels something like whiteheads (sebum-like) then depletes. Now, aside from it got bigger (pea-size), it doesnt deplete after pressing, one opening left which expels little "pus-like" liquid, harder, and less movable. What could this be?