Depressing Training

I was at the DeLand High School track this morning at 8am for an awesome track workout. It was early, still overcast and cool, and I was running right on pace. But things just can't be all good for me and just through the halfway point of the session and my bum foot starts hurting so much that I can't take another step.
I had to quit.
I didn't want to quit. I felt great. I was happy with the times I was running. I knew that I was going to be able to finish the session strong because it wasn't insanely hot (notice I did not mention that there wasn't any humidity...I still had plenty of that:). I want to be able to run fast in my races so that I can finish respectably (and earn points and win money).
But I just HAD to quit.
This is getting beyond ridiculous. I have no CLUE what is wrong with me...all I know is that I'm getting very mad at my foot and if I didn't have to use it, I would probably lose it!
So, I've been depressed for the remainder of the day...which involves a lot of self-pity, moping, eating, watching TV, and skipping other workouts. One good thing that I have been doing is trying to give my foot some TLC...self-massages, ice baths, stretching, etc. Anything and everything I can think of...of course it's not making a difference! Hopefully a day of mental frustration, followed by a good night of sleeping, will clear all the depressing thoughts out of my head so I can get back on track tomorrow.
I have used the down time in other productive ways...visiting my Grandmother, catching up on emails, shopping for housewares (I just purchased a 65 piece flatware set...yeah, I know, that's really what I need to start with...but wall paint, shower rods, toilet seats, and tile cleaners aren't nearly as exciting to shop for:). At least now I can eat with utensils in my completely unfurnished/unpainted/dirty house. Hey, give me some credit, I've got some class:)