Hello,
Do you have any food allergies? Food allergies can cause the "black eye". I would ask for a food allergy panel blood test, this might be the answer.
Precaution- While applying any cream or moisturizer or sunscreen over your face make sure you don't make any contact with the areas around the eyes. And If you feel an utmost importance to apply something there then you may get an under eye cream that I do not think is necessary.
Possible cause- Stress, Not Optimum Sleep, and impure blood.
You must drink enough water, fruits rich in Vitamin C and Exercise is always helpful. A multivitamin would be good.
Advise- A blood test is always the easiest thing to know your basic being of health.
Take care, Stay Happy!