In reply to Robbie1511:
What are the relevant facts?
What is your age, height, and weight? Gender?
Was your previous furthest walk 2 miles? So then have you gradually increased the distance walked, or have you gone from 2 miles to 25 miles in a week?
Does your job involve standing up all day long?
Have you looked at changing the lacing of your boots, as it is possible that you are not getting sufficient blood to the foot, or blood drainage?