Stress causes acne and acne causes stress...
Stressing about it is not going to help, only make it worse. Also stress causes other problems too, so the only solution is to find ways to make yourself happy so that stress does not take over. You think "I'm stressed", then you will be stressed. If you think "I'm allowed to be happy", then you need to take it easy. No matter what you're doing in your life, you have to find ways of making it fun so that it doesn't stress you out.
Any time you do something "stressful" just think "I'm doing my best and it's all I can do". Give yourself time for fun things as well so you keep your life balanced, and if it's people that are stressing you, needing too much attention (usually my case), just tell them you are trying to focus on what you're doing and you will get back to them when you have more free time.