as we get older, we can't bounce back from stresses to our bodies like in our early years.
i get this problem after 1 hour of standing in high heels!
heels are fine, but once we cross the line of wearing discomfort, keep the heels on until discomfort sets in. then go find a seat!
if you know you have to be on your feet for extended periods, try a lower heel or a platform shoe that doesn't make you stand on the balls of your feet.