Hi. I also have dark circles that at times show more than others. Sometimes this runs in families and has to do with genetic makeup, especially in those from European ancestry.
Dark circles under the eyes are temporary and caused due to insomnia,smoking, a family history of dark circles,deficiency of vit K in diet, allergies like sinusitis and eczema, and adrenal gland disorders.
Take rest adequately and eat healthy nutritious food containing lots of green vegetables. Try to avoid caffeine, because it promotes water retention and leads to the dryness of the eye. You should also apply almond oil or skin creams containing vit C or K,alpha hydroxyl acids and kinetin.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.