Painful Pimple on Penis

I am sexually active and about 3 or 4 weeks ago I had unprotected oral sex with someone I would consider questionable I suppose.  

Well Ive never seen anything to worry about around my penis before, but tonight while I was watching tv I went to readjust myself and felt a pretty fair amount of pain and soreness when touched the area. I looked at it and it looked like a pimple with a white/dark yellowish double head (it looked like there were two whitish heads literally touching inside a reddish area about the size of a pretty big pimple some people can get on their face in a bad breakout).
  
It looked similar to this but the heads were obviously in the middle -->  (..)  <--- I popped it and it hurt pretty damn good (mostly soreness) and got a small amount of puss followed by a pretty good amount of this oily, watery; graysih yellow liquid substance. And then when that seemed to be gone, a little bit of blood.  After I popped it, it started to itch.

Suffice to say Im scared ********, If it doesnt go away in a couple days im going to the doc. but I was hoping someone could give me an idea, does it sound like an std or just an irritated pimple?

[Vance2335]

Bumps can be many things and often not STD related, other then that only a Dr with an exam and possible teste will be able to tell you what it is.