Why do all my health issues show up on my face?

It's so depressing to see whatever issues i have going on with my showing up on my face in the form of either redness, paleness, dark circles, puffy bloodshot eyes and just generally looking like i've just quite a crack addiction or something. It gets really bad that i look like a totally different person. Surprisingly i don't get Acne though... i nearly wish it was just Acne that i had. Is this due to my detox organs not being able to detox fast enough? i eat really healthily and exercise and i'm not overweight. i'm nearly underweight to be honest.