I unexpectedly had a bad blood bank experience (after years of donating just fine.) It was a physical thing obviously. I think maybe I hadn't eaten enough. However, now it's emotional. I get fearful remembering and get woozy for every blood stick, even if it's for one little vial.
Just like everyone has suggested - I tell them, they have me lay down, and I carry a snack in my purse. I think having someone along for emotional support is a good plan. I'd talk to her about someone else. I like it when the tech talks to me about random stuff. At my lab, there are lighthouse pictures and figurines all over the wall. I start a conversation about those and it really helps. (It always cracks me up because no one ever knows anything about the lighthouses - they're really just there as a distraction! - It works!)