I had a few times where i broke out for no reason. One time a girl i was seeing start to use a new perfume (so i only broke out if she sprayed it on that day and i touched her). Another time a guy would spray his house with pesticides (he would spray his house all the time) and if i happened to be near by the wind seem to carry that mist toward me and i would break out later. Do you have your windows open? A friend of mine would break out from bugs coming into his bedroom at nite while he would sleep (the screen was not enough to stop the small bugs from some how getting in).