Why do I get pimples that seem to turn into craters after they are popped? (photos)

Red pimple like bumps come up on my butt. They either have white stuff or clear liquid come out when they r popped. However, after that they seem to turn into crater like holes and never go away. If they do it is intense scarring and lately they have came up in like a group. coarse I can't stop picking at them, but I swear they seem to come from something deep n my skin. Help pls, it's embarrassing to me.

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