painful cramps in bottom of foot and toe

I have been experiencing excrutiating cramps in the bottom (middle) of my foot and sometimes extends to the second toe from the left, on my left foot. I just noticed today that it is starting to affect the bottom of my right foot as well.
I have noticed these severe cramps periodically over the last couple months. They are starting to last longer and it is quite unbearable. FYI -I have started an exercise program within the last few months. But, I have never experienced anything like this in the past when I have started exercise programs.
What could be causing this and what can I do about it?