the dairy is an interesting point. dairy has apparently been linked in some medical studies to acne. have you been loading up on the milk and cheese since giving up meat?
beyond that, it could be anything- a hormonal change thats just randomly turned up now, bacterial stuff (in which case using a 2.5% benyozl peroxide based treatment might help), a change in the skincare products you're using, an allergy, the list goes on.
might be worth taking your skin to a dermatologist- who can see it,for a start- they'd be much more likely to be able to identify what could be causing it.