This kind of question doesn't make much sense to me. If you have a shitty diet, a Vitamin C supplement won't make much of a difference. In my personal experience, and in reading the journeys of others on this board, the road to smooth skin comes from a consistent, nutritionally dense diet free of junk food and intolerances.
What does your diet look like? Are you getting most of your vitamins and minerals from fresh, whole foods?
I had the same problem last year. Tweaking my meals before and after exercising, as well as the length of the workout, completely stopped the breakouts I was experiencing when I took up resistance training. I eat a light, protein and fat rich meal 2 or 3 hours before working out. I exercise for no more than one hour (this is crucial). After exercising, I wait about 2 hours until I eat.
It's also important not to exercise too much. Keep it to once a day, every other day.