I don't know about the milk, but I think I remember something about it (someone told me once, I don't really remember it all though).
But, I do have it (on my face of all places) and I've been breaking out in small patches in the last couple of years.
I now have it on the side of my elbows, and on the top of my feet.
I've been using a cream that my mother gets from the doctor she works for. I forgot the name, but it's some kind of steroid cream (not the anabolic kind of course).
That works well every time I use it.
Anyway, my point was, the research that I've done on it suggests that there can be many things that trigger it including stress, dry/cold weather and a bunch of other things.
I was also told that being out in the sun was bad for it, but personally I seem to notice that it's not as bad when I'm out in the sun as it is during the winter.
But stress is definitely a big factor. For me anyway.