Hi Folks,
I'm new here, and hoping to get some advice / pointers on a problem that has marred my season this year and I need to fix by next year, namely that I am prone to vomiting in high temperatures and it's ruining all my races.

I'll go into the details of 4 events shortly but in short when I am at Z3 or above in temp of 35 degrees or more it seems to result in my vomiting lots of fluid, unable to hold down fluid or foods which quite quickly results in me having to stop, here is how my season has panned out (I'm a beginner, but this is not my first year of Tri so I don't think nerves are an issue)

Mallorca 70.3, ate quite a big breakfast and probably drunk too much coffee then had a drama trying to source a new transition bag after getting done for bag marking (I know, I know). Felt mildly sick before the swim but pulled it together on the swim which resulted in a significant pb (by over 4 mins). I had myprotein tricarb in the bottles on the bike (I use this stuff all the time), had a gel abut 10 mins into the bike then part of a powerbar at the bottom of the climb. Started feeling sick on the climb, was sick. Suffered Di2 failure after the climb which resulted in me doing the rest of the bike leg with two gears, but wasn't sick much after. Total consumption was 1x gel, 3rd of a powerbar and 3x bottles of tricarb

A few mins into the run was feeling the heat and feeling sick, after the first aid station i was sick (lots of liquid) and the remainder of the run was spent sipping coke, feeling the heat and feeling thirsty and stopping to chuck up loads of liquid, my run time was about 20mins off a reasonable time for me to give an idea of the extent of the problem. Heat on the run upwards of 36deg

Rappi 70.3, lighter breakfast, no nerves, no bike issues, another swim blitzing last years time. 3x bottles of tricarb on the bike, started to feel sick around 70km and started to actually be sick on the run, again trying to get coke down on the run as this was all i fancied and felt like i needed the sugar. Pretty much the same result as Mallorca, time 20mins below what it should have been on the run and stopping every few km to be very sick, lots of liquid coming up. Temp was again in mid to high 30s. By the time I finished I was feeling desperately thirsty, tired to drink afterwards but kept on being sick, ended up on a IV saline drip in the medical room to sort me out.

Etape du tour, more heat but this time I decoupled fluid and food, I was on electrolytic drink and torq gels. I'm ill with some kind of chest infection and taking it easy, everything is going ok but on the Glandon I leave the gel a little late and instead drink quite a lot of coke at the top, it's at this point it's getting very hot too. I run out of torq gels and at the bottom of the last climb up to la Toussuire have the events gel. I'm sick about 20 mins into the climb and again have to keep stopping, being sick with lots of fluid coming up. I'm not so worried about time on this event so the last climb is predictably grim seeing as I can't take on any food at all. After I finish I sip a coke and am not sick again.

Swiss Alpenbrevet (another bike event), I have nuun electrolyte drinks, home made pies (scratch labs book) and salt sticks caps. Everything is going textbook well for about 7 hours, make the cutsoffs, pacing spot on, I feel fit. Have about 150ml of coke in two stops, still feel good, have a saltstick cap with each so I'm not too heavy on the sugar. We descend into a valley which goes down to about 300m above sea level and it's getting very hot, about 36 degrees. I start to climb the Lukmanier pass and start to feel sick, I stop for water and am slightly sick. 20mins later I stop again for a sprite because I can't stomach the idea of any kind of food, and I'm sightly sick again. Another 20 mins I stop again, no food for 2 hours at this point and am sick. I have another hour of climbing to the top and at my current rate will not make the next cutoff so I abandon. It's 40 mins back down to the valley and the train station, I'm still slightly sick as I get on the train. About an hour later I've recovered and am no longer sick. This was my main event this weekend, and the first I can remember a DNF, so I obviously don't feel very good about it.

So as you can see through my change of approach, my early theory was that carb drink + heat was a problem for me, later theory is that too much sugar vs salt was the issue, now I'm really not sure what is causing it. I can't reproduce this in training, but there are two things I want to achieve:
1. Prevent this from happing in short high intensity events like a 70.3,
2. If this occurs during long events work out a strategy to recover it in a known amount of time (ideally 30mins or less).

I'm hugely grateful for any advice that can be offered to get to the bottom of this.