babe if you're experiencing such pain, I think you should talk to your employer to see if they can make arrangements to lessen the need for you to stand for long periods of time. I had a few occasions where my back really hurt after long hours of walking but it would go away after I do some stretching or after some rest.. thou the dull ache seems to be there all the time.. if yours is really bad, you probably can go see a doctor but I'm not sure what kind of pain relief they can provide you.. perhaps you can also request for a memo so that you can use that to request your employer to lessen your standing/walking hours. Take care!