Why does my feet feel hurt so bad when I jog, jump or do stretches?

When I go to my community gym I get on the treadmill and jog for maybe around 4 hours then do a whole bunch of exercises. When I jump or jog or stay in one place to stretch, my bottom of my feet start to feel like they cramp up and it hurts so bad. I love to exercise but my feet stop me from doing certain things that help my body. I bought 8 different pair of Nike running shoes and my foot keeps cramping up. What can I do to relax my feet so I don't have to stop working out?
Why does my feet feel hurt so bad when I jog, jump or do stretches?
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