Not saying to quit exercise, but it could be all the physical activity you're doing.
I used to be a sports addict playing basketball, tennis, cycling and hitting the gym occasionally. During that period I broke out into cystic acne and there was just no end to it.
Ever since I quit sports completely my acne has become manageable. I only break out now if I eat the wrong stuff. I'm only able to identify what the wrong food are because regardless of what I ate when I was extremely active I would break out.
I have tested this theory by getting completely clear skin which takes me 3-4 months and then playing sports over a week period. I'm sad to say that I broke out horribly over the following week.