It was the Meds!!!!
I just ran The Train Robber's Enduro in Arkansas this past weekend and did pretty well , houring out at the last check 4 miles from the finish without getting sick. Conditions were 85 degrees at the start and about 95 when I finshed with constant high humidity. The difference this time is that I went off all meds for a week and then went to my doc and told him that he'd better find me a bp med that didn't affect my stamina. I started on a new one but not sure if I've built up to the therapeutic level yet but ift definitely cut down on the negative side affects. The reason I went off all meds is that I went to donate blood and my bp checked out high and was still high 3 days later when I tried again. I figured WTH, why put up with side affects if the med is not doin the job! Within 3 days I was feeling like 300% better (high bp has no symptoms) and my bp wasn't any higher than when I was turned down at the blood bank.
You see, I've had high Blood Pressure (hypertension) for 18 years, ever since I was 24. It turned out to be a genetic thing. They've had me on numerous meds to control my bp; beta-blockers, calcium channel blockers, Angiotensin receptor blockers etc. All had side effects, some severe and not all brought my bp down. The whole issue of hittin the wall became noticeable when I started into jujitsu with my daughter. Very physical 90 minute sessions with a lot of judo type throws. About half to two-thirds trough I would began gettin nauseated, dizzy, weak, etc. At the time I attritbuted it to poor conditioning and didn't push the issue with my doc. In hindsight I really should have.
The moral of the story is you know more about your own body than than the docs do and if they won't listen either be persistant or find one that will listen.