I never had a problem with acne, just a little during puberty.
Last year though, for some odd reason, I started breaking out. I went from having one tiny zit a month before my period to 20! I couldn't get a dermotogist appointment until March and this had happened in November. So I went to my regular doctor instead. He told me it was most probably from stress and the weather combined.
The secret: moisterize, relax, and moisterize again.
It had clear up in a month. By the time it was tanning season the scar had left too.
I also suggest you use a mild cleanser for your face like Cetaphil.
Lots of water also helps.