Acne are your body's attempt to get rid of unwanted toxins, you already know that.
I would like to ask you, what is your fat count in your diet? By fat, I refer to the fatty acids (Omega 3 and 6).
A fact I stumbled recently, is that the preferred ratio between omega 6 and omega 3 should range from 1:1 to 4:1.
For experiments, I use cronometer.com, payable app that helps you track nutrient intake. I believe there is a mobile version too (it's payable, though,)
First, try to balance your omega6/omega3 intake.
Give it a week.
Then, try hydration as well. Water plays huge roll in digestion and detoxification.
Also, another thing I recall is Zinc Deficiency.
While we vegans/vegetarians tend to eat a lot of fiber and phytates (which are healthy, of course), many of us don't know that it may lower zinc absorption in the body.
I hope this is helpful
I was born vegetarian. Am I Blessed?