You need to wear sunglasses and sunscreen everyday. I am wondering if you have an iron deficiency. Start eating more spinach salads, creamed spinach. See if it goes away. You can also use a concealer to cover them in the meantime.

Some reasons people experience dark circles under their eyes are;
1. Lack of sleep
2. Poor diet
3. Over exposure to the sun
4. Dehydration
5. Allergy
6. Aging
7. Hereditary
Make sure you get plenty of sleep. Also its good to use green tea or chamomile tea bags as a poultice under the eyes. Cool not hot. Massage the eyes with almond oil, Drink plenty of water and wear sunglasses to shield your eyes from the sun. Each fruits and veggies rich in vitamin E C and iron.