I went in for a physical as I used to do every year and that's how I found out. Luckily the time I started taking the creatine was just two or three months before my physical. The creatine content was not soaring high, but it was a bit over normal content.
As for the breaking out, that was my experience and I know a couple other guys who started taking it and the same thing happened. I was 20 and it was not like I was going through puberty and that was the only additive I was taking at the moment with Whey Protein. I know it was not the whey protein because I took that in high school and never had problems with breaking out, other than your little pimples here and there once in a while.