I've got a somewhat similar problem.
Blood and guts don't bother me, whether it's mine or somebody else's. I've had bad cuts, stuff stabbed in me that I actually watched the Dr. cut out after some local anesthesia. I've had a surgery where they left the wound open to heal up by itself and I had to push gauze into the hole with a q-tip for a month everyday. I can bleed all over the place and it doesn't bother me.
However, I can't stand to have blood taken into a vial. I don't care about needles, or shots, or IVs, I've just never liked having blood taken.
At work, besides my normal job, I'm also a HAZMAT technician. I have physicals every year which include all kinds of blood sampling. About three years ago the nurse was taking my blood and everything went fine. 10 minutes later while I was waiting to have a chest x-ray done I pulled the bandaid off of my inner elbow and there was a knot the size of a marble where she had taken blood. She had torn the artery and over the next couple of days my whole forearm turned black and blue. This just turned me off a little more to having blood taken.
Two years ago when I went in again for the same thing I joked with the nurse to not turn my arm black like the one did last year. She assured me that she wouldn't. Turns out that she sucked even worse. My veins are pretty visable and she proceeded to stick the needle in my are and started prodding around trying to get it into the vein. It seemed like 10 minutes before she got it in and by this time I was sweating, had the chills and was very light headed to the point where I thought I was about to pass out. I actually sat in the chair for about 5 minutes before I thought it was safe for me to just stand up!
Here I am a 6'2" 250lb guy about to pass out over giving a couple of little vials of blood. I was thoroughly embarrassed. And ever since I've gotten the same feeling though I try to play it off a little better. I've been knocked out several times, but I've never felt like I was going to pass out except for these occasions.
If anybody calls me a wussy, I'll whip your ass. [;)]