QS - Your problems are almost over.
I had a bad experience as a kid when they tricked me and freaked me out with a shot, caused me to pass out & they had to wake me up with ammonia or 'smelling salts'.
For years, every time I had to get a shot or have blood drawn, I'd get light headed & have to put my head [strikeout]up my[/strikeout] between my knees for a looong time till my BP came back up or whatever. It was all in my head. Not that it was imaginary, it was just that conditioned response to seeing the needle.
Then eventually I went on active duty rather suddenly (I P.O.'d the local skipper, canceling out of a program and requesting active duty, so they got my orders and "misplaced" them until [b]after[/b] I was supposed to report, and sent the Sheriff out after me one night).
After some school, I was right where I think you are, except I was about to prepare for overseas duty with the Gulf of Tonkin Yacht Club and you are not in that branch, if you are at Camp Atterbury (sp?).
Anyway they gave me these "shot cards" and it looked like I was getting a needle for one of every vaccine they could think of, except for something they were using the needle-less machine for.
I thought I would drop flat on my face and not sure if I thought it would be the actual shot or the fear of embarassment that did it.
However when the moment of truth arrived, I looked away, and they were barking at us and jabbing us with one needle then another, and frankly I didn't have a chance to freak out or pass out. It all worked out OK, and that pretty much cured me.
If they are still using the high-pressure gun, just be sure and hold real still no matter what and it will go fine. If you jerk your arm, you may make a bigger hole than necessary, and if the serum doesn't all go in, you may have to do a repeat on that one.
However, the other guys are right about people who don't know what they're doing -- avoid them at all costs.
Lab tech (experienced): OK, some so good you cna't even feel it.
Lab tech (learning) avoid like the plague, (often will have someone coaching them)
Nurse: Usually pretty good, but if they look butchy, find an excuse to get someone else to do it.
Doctor who says, "Here, let me do it, I haven't done one of these in a while": BAAAAAAD!!!!
You will be fine, soldier.