Once I got back to the car I used ice from the cooler on the area and it went away, itch
Now I would like to know what happened, I'd hate for
it to happen again.
I was sweaty of course, though it was not a new deodorant actually one I've used for years, nor a new detergent. It was a relatively new bra that had been washed but not all cotton.
Thank you for your input, this really put a damper on an otherwise great hike!