It's really weird, but since I live my life healthier, I get strong reactions to stuff I've never had problem with before.
Deos, for example. I used to use the regular stuff, whatever you can find in a regular drug store and never had a problem. About 2 years ago I have switched to a natural kind of deo with no fragrance and no additives and a couple of weeks ago, when I tried one of my old favorite (just because I wanted something with a nice scent for a change) I got a rash too...
I didn't do much with it, just used some calendula cream overnight as the skin seemd to be dry and it got better in couple of days.