I've had this before, it's called "heat stroke". It's harmless like a hangover, unless you're stuck in a desert with no relief for hours. The headache is caused by dehydration. Make sure you drink lots on hot days. Take care, Laura
something disturbed your central nervous system, maybe a viral infection.
take note of the event and keep logging over the next weeks it can be very helpful.
CBC with ESR can possibly reveal indirect signs of infection.
had you eaten anything before this happened I am thinking low blood sugar Hypoglycemia , could also be dehydration are you drinking plenty especially if you live in a hot area .You need to drink water all the time to keep hydrated ..