I am a runner. I took some Excedrin today because I had a headache , about five hours before my workout. I use to take Excedrin to improve my running, but when I did, I had a numbness in my calfs and my feet, as I did today during my running workout. After I d stop running, my normal sensation comes back. It almost felt like my legs and feet were swelling, but numbness. Why does this happen to me, and is it dangerous ?