Moving my bike cleats back just 1/2" requires a whole different movement to click out (un-attach my shoes from my pedals when I stop so that I don't tip over). Photos of the subsequent bruise can be available upon request.)

Riding with a migraine = bad idea.

If you have a bruise from tipping over with your feet attached to you pedals
AND
you have a migraine
AND
you're a bit sick to your stomach from the headache...

AND
You see lightning ahead

YES...it is okay if you turn around and go back after just 4 miles.