Other things to think about:
How long the discomfort lasts?
Activities the previous day that affect your feet (high heels, perhaps?)??
Do you routinely perform stretching exercises?? I remember a lot of them in my yoga class, and they really felt great.
I still remember how tight my hamstrings got back in the days when I did aerobics. Ow!
Hope you figure it out.
A fruit is a vegetable with looks and money.
Plus, if you let fruit rot, it turns into wine,
something Brussels sprouts never do.
P. J. O'Rourke, humorist