Thanks for the help!

The link didn't work for some reason, so I did a google search for 'hot foot'. The articles I'm reading describe it as very painful and often caused by tight shoes or small pedals. I have loose shoes and platform pedals, but still got me thinking . . . I had it happen once before, only mildly, and I was wearing the same shoes that time.

I'm going to try different shoes! Thanks for your help, Kalidurga and Tulip!