Hi dear it seems that you have done extreme diet and exercise thus your nutrition store has replenish and thus because of that you are suffering from dark skin and dull face. First of all you need to check your diet for nutrient rich and low calories diet. You should increase intake of coloured fruit and vegetables. Also protien intake need to be checked.
Next Steps
You should start having fresh fruit and veg along with plenty of water. to replenish your skin. Also face pack like honey and lemon will help to brighten and glow.
Health Tips
you can consult me via direct consult for more detailed diet chart.