The most likely cause for such a pain in your foot seems to be due to diabetic peripheral neuropathy
Prolonged standing and associated VIT B 12 deficiency might be contributing to your symptoms of foot pain.
You must consult your doctor and get proper physical examination along with other relevant investigations like nerve
conduction studies along with arterial and venous doppler of both legs and VIT B 12 estimation.
If VIT B 12 deficiency is found then take injectable VIT B 12 for 7 to 10 days after consulting your doctor.
If diabetic peripheral neuropathy is diagnosed then treatment involves
Tight blood sugar control
medicine like PREGABLIN
Anti depressants like DULOXETINE
Opiods like TRAMADOL