I had blood work done today (1 vial, to test for iron deficiency). The site (left arm) never before bruised, but today, after several minutes of applying pressure (as directed), the vein was swollen, bruised and red spots (like blood spots) appeared under the skin. That was 6 hours ago. It now has grown to nearly an inch long, is both itchy and minorly painful. The nurse did not ask if I had any allergies (I do, to latex), and I wonder if that is the issue? My left hand hurts a bit as well, a dull throb (this is not normal). Should I be concerned?