Why am I breaking out now? I need help.?

I have never had severe acne, I got one or two occasionally but now, I'm 19 and I am being bombarded. I don't mean to be overly dramatic but it is tearing apart my life. I met this really cute guy and we went out 4 times and he asked me to be his girlfriend and I was so happy. Then about two days later I broke out, overnight this insane amount of acne on my chin and cheeks, its repulsive. I avoided seeing him and canceled a few times, then he just stopped texting and calling me. I am also really moody, when I catch a glimpse of myself in a mirror I am just grossed out, I don't like going to out and I don't know what to do. I've been to the derm, they have no idea, I'm not stressed out, I wash twice a day and have completely abandoned make-up. Whats happening to me?