Hi,
Loads of great suggestions. I guess everyone is different and it could be absolutely any of the above possibilities, but I do resonate a lot with the previous poster.
I am a vegan, and I found that once I stopped eating dairy, my skin cleared up. Not overnight - I still get the odd spot around the chin area, but I have read that spots in this area indicate weak kidney energy, and I have been prone to cystitis in the past (which, is aggravated by meat and dairy, amongst other things).
The raw foodist way of eating could be something to look into as Peter Mitchell said. I agree with a lot of their philosophy, and am starting to up my intake of raw fruit and veg, as well as learn to prepare simple raw meals as I'm interested to see if I get the plentiful amounts of energy that raw foodists speak of.
Even if you couldn't make the leap to that straight away (and it would take some research), progressing towards reducing processed foods and cutting down on meat and dairy might be a good start. And think again about your kidneys - perhaps your body is trying to tell you something. Have you had kidney trouble at all?