When I exercise (vigorous cardio) after about 15 to 20 minutes the second and third toes on both feet go numb, and when I look at them, they are completely yellowish/white from the base up. The rest of my foot looks normal. I know it's not shoe tightness because I don't wear them during my karate class when this most often happens. Just as a note, I have a similar kind of numbness problem in very cold conditions since my feet got extremely cold and numb one time while working outside. Thank you for any information on what this could be.