Getting Headaches - NOT migraines after Infrared Sauna use

I am hydrating - in good health and yet have been getting headaches - hurtful ones after Infrared sauna use. Any ideas or suggestions? I hydrate - LOTS - use electrolytes first - and don't know why the sauna FEELS great / but the aftermate hurts - i've only used it 3 times - could it still be detoxing?

Blessedly - I'm fine -was not getting enough salt and peeing out all I drank - Today was day 2 in the sauna and thrilled to say NO HEADACHE as well as this is not steam / this is dry infrared.

Case closed - I'm delighted~~ thank you. Adrian