Glad your doc is responsive. Yup, warm + red + almost always means some kind of infection. Gosh, with your medical history, wish I could lend you my veins. I have absurdly sensitive skin, but getting blood drawn is never a problem. When I go to donate blood, if there's a trainee, I'm the one they send that person to. My elbow veins are quite visible, pretty big and you could spot 'em from across the room. I never have a react there.

Mind you, if someone walks by wearing perfume, THAT I react to, or if my skin gets any kind of scratch THAT it reacts to, but giving blood's never a problem.