My dad passes out every time he has a needle inserted into his body, be it for vaccines or blood tests.
Every time he tells the nurse "I am going to faint", and the nurses are "noooo don't worry, silly" followed by "OH CRAP"
I almost faint myself when I get needles in me (although IV ones, not vaccine ones). That was the funny thing about the colonoscopy: they had to IV me just in case. I was more worried about the IV than the procedure. After I nearly fainted from the IV, they insisted on medicating me, and it took a bit of arguing to prevent that.
For the record, take the medication. It makes the procedure easier as well.
Anyway, that sounds terrible, but that's the fun of owning a nice, shiny human body. Physical change requires extreme amounts of pain - in nature it prevents the organism from making unnecessary changes by requiring a huge amount of desire to complete the act and overcome the pain barrier. I mean, animals gnaw off their limbs, and that's an instance that hurts just as much and DOES leave the animal permanently damaged. Just remember that as bad as it felt, you weren't in serious danger, and it was all to improve your body, not permanently damage it. When pain loses its fear/psychological component it becomes far less potent. Still, I'm sure it was hell, but a hell with a purpose at least.
That colonoscopy, however, was just an unnecessary procedure that served to teach me a valuable lesson about medicating during operations

And despite all the pain I went through, I received no actual physical damage. Funny how you can hurt a lot without actually being injured. What I did learn, though, was that when I relaxed and stopped fighting the pain, it diminished a lot and the procedure went better because I was going along with the change/pain. A lesson to remember for my entire life. I actually sort of want to go back and do it again. Practice makes perfect, you know (I'm nuts!).
My point is, at least try to use the experience as a lesson on the nature of pain. You'll get something out of it at least.