Those were dizziness, vertigo, convulsion, nausea, headache (mostly vertex).
Those are symptoms of hyperthermia.
If the symptoms are light, take a lot of water (Gatorade is very good) and stay in cool place.
Of course, I can help you by acupuncture if you want.
Last summer was not so hot, but this summer is good in hot (for me).
So you should be careful.
However in some cases, you better not be careful...
Beat The Heat (click here to read the article).
This result is interesting,
but don't try this method unless you really really need to do high performance.
And it is so danger, "cycling with shoving thermometer up your butt". （१▽१*）