I gave blood today for the first time. I m 17 years old, definitely in the height and weight range. I felt completely fine after giving, not even lightheaded, then two hours later a headache started manifesting, I felt really dizzy, and I ve felt lightheaded ever since. I donated blood at 10 o clock this morning, and it is now 645 pm. I m extremely cold , and blankets aren t helping. I thought I had a fever , so I checked my temperature, but instead of being HIGH, it was really LOW- 97.4 degrees. What s going on?