Needle poked at rave HELP!! HIV?

I was at a festival on Saturday night and was just watching an act when someone brushed past me and I felt a poke on my bum cheek, it didn't hurt or feel like it went in far, just kind of like a light pin prick. There is now a very small red dot there that looks a tiny bit like a spot but there was no blood at all. It now sometimes feels like a dull ache but im not sure if im imagining this because im so paranoid or not. All of my Skin was covered up apart from the tiny bit of my lower bum and my thighs so this area was exposed to whoever poked me. I've heard of people going round at raves poking people with needles to infect them with HIV. I am just wondering what are the chances of this happening to me? I'm going to the doctors today to get checked but I know it won't actually show up for 3-6 months, I'm just getting really scared and paranoid and I wouldnt be surprised if someone had done this as about 90% of people there were off their heads on drugs. Please help! Thanks :)