Whoa, that sounds awful. You have ALL my sympathy. I had a bad reaction to getting my blood drawn the first time I had it done as an adult, but not as bad as you had it! I hope my advice can be of some help, nonetheless. I always, always, ALWAYS insist the chair be tilted back so I can lie down. If I'm sitting up I will probably pass out, but if I can lie down I can relax more and it keeps my blood from deciding to all drop into my feet, or whatever it is that it does when I pass out like that. Lying down also makes it easier for me to focus on breathing deeply and evenly, and to look away from what they're doing, as seeing the process happen makes my brain flip right the hell out. I also have someone go with me if possible; the moral support helps a lot. I also protest, loudly, if the nurse looks like they're going to try to dig around for a vein. A nurse experienced in blood draws shouldn't do this! I have to get my blood drawn regularly, but making sure to do all these things has made it go from a terrifying experience to something unpleasant but bearable. Is it possible your antibiotic may have upset your stomach some? Even an antibiotic can do wacky things taken on a n empty stomach if it's usually taken with food.
Yeah, get it done lying down, ask them if they can use a small needle- it'll need to be in you longer but you'll feel it less. They use pediatric needles on me because I have bad reactions as well. Definitely check your antibiotic and see if it needs to be taken with food. If so save it until after you've had breakfast. They might have juice/muffins on hand for you to eat once you're done. Since you have to do it fasting- yay food! but also the sugar gives you a little boost. Don't get up immediately after if you're still feeling dizzy. Most vamps totally understand most people don't like getting blood drawn. Let them know ahead of time that you have bad reactions. If you go in soon they'll probably remember. A lot of them will have suggestions to help and'll tell you what's available to make it easier. If they don't have snacks then pack something. That sugar boost is a godsend for getting you ambulatory. I brought in one of my stuffed toys during a particularly bad week so I had something familiar and comforting to focus on and no-one batted an eye. If you've got something like that or a stim toy or anything as a pleasant distraction that might help with the natural anxiety.
Bringing something comforting or distracting can be really helpful - using one of those squeezy stress toys with the other hand, for instance, or listening to music. Sometimes I turn my head as away from what they're doing as I can, close my eyes, and start counting downward from 600 in increments of three. I have a pretty bad response myself if they take too long to find the vein, so I usually tell them about that in advance and ask if they could let me cool off for a moment if they're taking too long. This usually ends with them checking if I'm okay a kind of annoying amount, but it's better than the alternative. It might also be worth seeing if you can be prescribed some sort of anti-anxiety medication to be taken before situations like this?
-hugs- Drawing blood sucks for most everybody, but it extra sucks when you don't take it well. Hope you're not like me and don't have to do it too often.
This may sound odd, but hear me out. Watching them stick you can be a big part of the anxiety and not seeing it can help a lot. The problem is it's hard to resist looking. Solution: Get a cheap sleep mask at the drug store. They might be hard to find, but a large drug store will often have surprising old-fashioned stuff on the bottom shelves. Put it on after you lie down on the exam table. Put on your headphones and stick out your arm.
Late, but: Make sure you're VERY well hydrated the day before. It'll be easier to find your veins and the vial(s) fill faster. See if they can use a different draw style? There's a variety of needle diameters and whatnot. I can never seem to get a good draw off the ones where it's just a fat needle stuck directly to a vacuum test tube. They have to use the one where it's a bitty needle on a long flexible tube + vacuum tube Also, amusing sympathy anecdote: I've never had problems getting blood drawn/donating, but Husband absolutely refuses after the one time he attempted to donate (after much pressure because he's a rare-ish type) because... Insertion was fine Donation was fine Then he stood up, and promptly passed out and "broke a table with <his> face" ... That was broken nose #2
Also, a mindset thing. An old Jedi mind trick you can play on yourself! It can feel embarrassing or imposing to tell the medical staff about your "special" requests. But really, they want to know these things! They want to do a lot to accommodate you! It's so much easier for them to have you lie down or look away or have a comforting squeezy than to have to pick you up off the floor or clean up. So don't think you're imposing on them. You're really helping them.