Very nice skhill! Enjoy your beer. 
Anelia, I wonder if you aren't dehydrated and/or overtrained, the way you've been describing your workouts. Has your resting heart rate gone up?
This week has been a little bit of a bust for me, with a houseguest and the motorcycle races this weekend. 20 again on Monday, a quickie Wednesday, bridge repeats Thursday and I'm going out for a quick loop yet this afternoon. I've pretty much made my footwear decision for the marathon - which is not the nice light Nikes I really want to wear but seem to be hard on my Achilles, but the brick heavy Brooks that I've done all my long runs in so far. Ah, well. Not like I was going to be setting any PRs this time in any case.
Speed comes from what you put behind you. - Judi Ketteler