@geo You are right, I should have specified the H+ portion of the lactic acid was building up (acidosis). Have you had your headaches checked by a doctor? If it isn't migraines, do you have high blood pressure? If you haven't already, you may want to look into a CT scan to rule out anything life threatening. It is NOT normal to have a consistent headache for 4-5 days!
Time for my update: I ran W8D1 today which on my program is the beginning of the final week. It was a 28R. I feel it went well, although I went a little slower than I did Friday because I figured I may have pushed myself a bit then, causing me to walk a bit. This time I merged my old route with my newer one to get the extra distance needed for the 28 minutes of running (tacked on the 1 mile portion on the left before heading to the ~2 mile slightly truncated portion I had been doing on the right). Technically, it is supposed to be 2.75 miles at that amount of time but I came in a little short before the timer ran out. Still averaging ~11-12 min miles.

Now I need to decide what to do after the end of the program. I think I will continue the 5k distance for awhile (sans program) until I confident in my speed, then might try one of those bridge program to ramp me up to 10k. I really like the program pushing me so I don't want to lose that. I also don't want to jump into another program before I am ready either. Decisions, decisions! What are all of you thinking of doing after "graduation?"
Haven't heard from some of you in a long while. Still with us?