I have no clue what they are. I call them cysts when explaining them. Basically i have been getting these blood and puss filled things on my stretchmarks. It used to happen once in a while but for the past month they have been popping up everwhere. New places have been my butt crack (as far as i know, no stretchmarks there) several on my very inner thigh, one is currently brewing while the ther is currently bleeding, and on the underside of my stomach "flap". My stomacg hangs a little bwcause since having my son. I cant shake that baby gut.  They are deep purple with blood and when popped blood flows out ofnthem. They feel like they have a pit in them, like a pimple, but i havent been able to get anything out besides blood and sometimes a clear liquid.