Bikrams after having heat exhaustion?

Hello!
Not sure where this fits in, but just have to get some feedback about my recent experience.
I’ve done hot yoga (Bikrams) sparingly in the past a few times a year and always done well with it (I love heat, spending lots of time in our home infrared sauna). Even my first time until now I’ve never had to sit out a pose. So I was very excited to start a 30 challenge yesterday, but the class was a complete failure. Half way through I got a bit dizzy (normal) but then got nauseous and had to lay down the whole rest of the class. Every time I tried to get up I just felt like vomiting. I was sure to cover all bases; the class was at 11am- I had a fruit smoothie earlier in the morning, a handful of trailmix, then lime water with a sprinkle of Himalayan sea salt, and lots of water the night before, calcium magnesium supplement, and more water in the morning. Even in the past I had not done that much and still floated through a class.
However about a month prior I had heat exhaustion from a few days of hot humid weather and it took a while to recover and eventually turned into cold. Ever since then when it is really hot out I get a bit nauseous while power walking to work (in sun, 45 mins) and generally won’t feel tops the rest of the afternoon or evening.
I’m just wondering if this is why my class yesterday was a failure and if there is anything I can do to help this problem. I want to give the class another try but am scared that this is going to happen again!