text: what is it when you start getting sort of sore/pimple on you bum.? just wanted to ask about this because i know its an std which i've just picked up from a girl i just met not long in the summer, and now this is the 3rd time since july that i get these sores on my bum...before i go to the doctor ( which i'm scared of) i just wanted you to tell me something just incase the result is bad for me. don't jump to conclusions...see a doctor if your worries but its probably just a pimple, or more likely an ingrown hair. maybe a cyst, also really common in people of all ages. it probably burns from all the friction of standing and sitting,just moving around. i wouldn't say it's an std seeing as how this is on your backside and most std's show up on the front.