Questions...

I've got a question or two and I apologize if this is the wrong place to ask it, but I'm a little confused.

I'm 24 and I'm in the military in Arizona. I had an injury as a child and since then have never been good around blood or anything like that.
I've passed out a few times getting my blood drawn and what not, but twice it's been different.
Twice when I've passed out, instead of just going limp my whole body goes crazy.
I get tunnel vision and then my eyes roll back into my head, I break out into a cold sweat, my neck swells up and I stop breathing.
My face turns bright red and then a dull grey, all my muscles tense up and my body turns rigid and finally I loose consciousness.
The first time it happened (3.5 years ago) the doctors told me that I was dehydrated and dismissed it as normal.
The second time was just recently and I was in perfect health.
(I'm running a marathon in one week and have been making sure my fluids, foods, vitamins, etc... are all right.)
So the doctor, this time, dismissed it as me "falling asleep."

Obviously I know when I'm asleep and when something's wrong... and something was wrong.

My doctor said it's possible it could be from Post-Traumatic Stress Disorder.
But what actually happened? Was it a trauma induced seizure, or was it some crazy form of regular fainting?

See, the main reason I'm curious is I believe the doctor thought it was a seizure, but he wanted to keep my record clean.
I have no history of seizures before I joined the military so if he reports a seizure I get disability when I get out in three months.

So I want to know, was what I had a seizure? And if it was, what would I be getting myself into if I had it put in my records?

Thanks for your time and answers.