Woke up with a bump low on my bum , squeezed it thinking it was a pimple & stung ! looked at it , it's a swollen pink, red bump. it hurts. what is this?

Pimple or Boil?: This could be an acne-like lesion or an infection or possibly something else. You may want to hot pack it for a few days and see if it comes to a head a drains. If it continues to swell and get larger and more tender, or if you are feeling ill, go see your doctor.

Infection: This is most likely a bacterial infection of a hair follicle or a cyst associated with a hair follicle. If it doesn't start resolving spontaneously in a week or so, systemic antibiotics may be beneficial.

Probably a pimple: Many pimples do sting and look like you described it. If you have prescription acne cream apply it otherwise get the retin a (tretinoin) products over the counter and apply a thin layer. When in the shower use salicylic acid wash to wash it each day. These take more than a week to resolve. Avoid picking pimples it causes the bacteria to spread and causes scars, .