What Did I Do To Myself

Absolutely. Stopping sweating/chills is the signature of heat exhaustion. It can take many days to fully recover...in my experience, it takes about the same time as getting over the flu.

It could be caused by any one or combination of these. If you stop sweating, particularly when coupled with unusually flushed skin, feel cold when you clearly shouldn't, get dizzy, have vision issues (spots, tunnel vision, blurry), or nausea not caused by nutrition issues, I'd slow down or even DNF. I think people in very hot climates mistake hyperthermia for dehydration and put themselves in a bad/dangerous position by taking in extra fluids and just pushing through it. And remember, no amount of training, nutrition, electrolytes or hydration (except for ice water, though not because of it's hydrating properties) can compensate for a core temperature that's gotten out of control.

ETA: Not a doctor, but as a native Floridian I've experienced heat issues many times myself (the worst occasion was to the point of vomiting, blurry spotted vision and disorientation), and seen others hospitalized. It becomes pretty easy to spot.

Don't think that I bonked.  I've been there and done that.  This was totally different.  Now that I have looked into it, I feel like it was early stages of heat stroke....stopped sweating, dizzy, nausea.  I wasn't very smart to continue but that male ego kicked in.

Plan to take off  till Saturday and try a slow run then.  In the meantime, I'm drinking a lot more than I usually do and staying out of the heat.  Thanks for the suggestions!

To re-iterate what others have said,  these are classic symptoms of heat - exhaustion / heat - stroke (two different things, and it seems that you were suffering from or on the verge of heat stroke,  much more serious.

To add to this though, once you have been a victim of heat - exhaustion / stroke,  you are more susceptible to future episodes.  See your doc! 

After reading thru the article and some information here, seems like I probably had the possible beginnings of heat exhaustion.  I'll be on the watch for this?

Any suggestions about how to ward off the heat exhaustion before it develops?  I don't seem to have this problem while training, only during the run portion of the two sprint Tri's.

• Drink even when you're not thirsty - you need to constantly think about how much you're drinking.  You need to replace what you're sweating out, and then some.

• Drink electrolytes (sodium, potassium, calcium...) when you're sweating a lot to help your body absorb the water you drink.  Gatorade for example.

• Eat bananas.

• Get yourself a well ventilated, light colored hat for the run. 

• Try to avoid races in hot and humid climates. 

So thought my friend from Va. Beach when she moved down here. She wound up on the side of the trail with strangers trying to take her to the hospital after an 8-10 mile run (she even brought her 2L Camelbak despite assuring me it would be unnecessary). And that was on October 28. It serves as a warning that even after you've spent all summer acclimating, when racing in conditions which might be only marginally different from your training, things can fall apart shockingly fast. Once your body temperature hits that critical point, it's a very steep drop down the other side.

As far as the OP, may I infer that the run portion of your sprint tri is happening a bit later than when you would normally be running? The extra 3 or 4 degrees of heat, combined with the stress of having just come from the bike-run could be enough to push you over the edge.

Also to the OP, where are you? What sort of conditions are we talking about?