I've had similar experiences, and yes it can be frightening.
But I know I have allergy/intolerance/sensitivity problems, which can lead to such rashes and even flu type symptoms.
In normal life I'm careful to only use certain shampoos, shower gel and washing powder. And I always put my clothes through and extra rinse or two.
However, when on appointment, I have no control, I'm showering in her body wash, bathing in her perfume and lying on her bed, sometimes I even get a tingle in my nose letting me know that I'm going to suffer in the next few days. But I'm a glutton for punishment.
Lynx deodorant in particular is a product that I'm very sensitive to. So it's very possible that your rash may be due to your own aftershave or deodorant.