mmmalis

hello. if you have a cold or a type of virus and your dr does a CBC with a differential you might have something called a "shift" in your white blood cell counts ie your neutrophils might be higher and your lymphocytes lower. if you have some type of bacterial infection your white blood cell count as a whole will be higher.
as far as affecting tests the dr will be looking at JUST for anemia i would say you don't have to worry. the hemoglobin, hematocrit, RBCs, and ferritin should not be affected by being sick. neither should B-12 or folic acid.
as far as the excedrin migraine, if you are taking the one with aspirin that might lower your platelet count slightly, but again that won't really affect the anemia counts.
hope this helps -- feel better.