I have recently started running(3 weeks or so) and I am still having leg problems..

The problem is about 4-6 minutes into a run or jog my leg starts to cramp and feels very tight and painful.. Its the muscle opposite you calf muscle...So looking down at your legs its the muscle on the outside of your lower leg--Flex it by pulling your toes up..

Anyway this muscle becomes so tight that I cant run and can barely walk until it eases up.. It seems as if pressure builds up and I cant run, jog.. My feet are VERY flat, so that probably doesnt help..

I need to increase my running distance ASAP--
Any suggestions on what to do?
I have an appointment with a podiatrist tommorow, dont know if they can help