I never had foot crams..well sometimes when i stretch my feet but not much. On the other hand i had back of knee cramp badly . It was at night , i suddenly wake up with a baaaad cramp . it took hours to go away.
Some drs say that could be due to low potassium levels. In my case i'm sure it wasn't that cause i eat potassium always.
Next thing would be YOUR MUSCLES. Think muscles and go back from that. in other words, if muscles cramp..what is realated to making the muscle cramp.. then i would say NERVES or blood flow i guess. So go for a neurologist or go get blood test done.
i've had a lot of foot numness lately. went for blood test, test results were normal.. so i went to a ft doctor, he said numness could be caused by a problem with the sciatic nerve.